diff --git a/HandsetDetectionAPI/HDCache.cs b/HandsetDetectionAPI/HDCache.cs
index 088b30b7..0b23fcda 100644
--- a/HandsetDetectionAPI/HDCache.cs
+++ b/HandsetDetectionAPI/HDCache.cs
@@ -1,10 +1,14 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Specialized;
+using System.IO;
 using System.Linq;
 using System.Runtime.Caching;
+using System.Runtime.Serialization;
+using System.Runtime.Serialization.Formatters.Binary;
 using System.Text;
 using System.Threading.Tasks;
+using System.Web;
 using System.Web.Caching;
 using System.Web.Script.Serialization;
 
@@ -13,20 +17,15 @@ namespace HandsetDetectionAPI
     public class HdCache
     {
         private static int _maxJsonLength = 40000000;
-        string _prefix = "hd4-";
+        string _prefix = "hd4_";
         //int duration = 7200;
-        ObjectCache _myCache;
+        readonly MemoryCache _myCache = MemoryCache.Default;
         CacheItemPolicy _policy = new CacheItemPolicy();
         JavaScriptSerializer _jss = new JavaScriptSerializer { MaxJsonLength = _maxJsonLength };
 
         public HdCache()
         {
             _policy.AbsoluteExpiration = new DateTimeOffset(DateTime.Now.AddHours(24));
-            NameValueCollection cacheSettings = new NameValueCollection(3)
-            {
-                {"CacheMemoryLimitMegabytes", Convert.ToString(200)}
-            };
-            _myCache = MemoryCache.Default;
         }
 
         public T Write<T>(string key, T value)
@@ -36,7 +35,7 @@ public T Write<T>(string key, T value)
             {
                 if (value != null && key != "")
                 {
-                    //  string storethis = _jss.Serialize(value);
+                    // var count = _myCache.Count();
                     _myCache.Set(_prefix + key, value, _policy);
                     return value;
                 }
@@ -58,7 +57,13 @@ public T Read<T>(string key)
             try
             {
                 object fromCache = _myCache.Get(_prefix + key);
-                if (fromCache != null) return (T)Convert.ChangeType(fromCache, typeof(T));
+
+
+                if (fromCache != null)
+                {
+                    T item = (T)Convert.ChangeType(fromCache, typeof(T));
+                    return item.Clone();
+                }
             }
             catch (Exception)
             {
@@ -86,4 +91,39 @@ public bool Purge()
 
         }
     }
+
+    /// <summary>  
+    /// Provides a method for performing a deep copy of an object.  
+    /// Binary Serialization is used to perform the copy.  
+    /// </summary>  
+    public static class ObjectCopier
+    {
+        /// <summary>  
+        /// Perform a deep Copy of the object.  
+        /// </summary>  
+        /// <typeparam name="T">The type of object being copied.</typeparam>  
+        /// <param name="source">The object instance to copy./// <returns>The copied object.</returns>  
+        public static T Clone<T>(this T source)
+        {
+            if (!typeof(T).IsSerializable)
+            {
+                throw new ArgumentException("The type must be serializable.", "source");
+            }
+
+            // Don't serialize a null object, simply return the default for that object  
+            if (Object.ReferenceEquals(source, null))
+            {
+                return default(T);
+            }
+
+            IFormatter formatter = new BinaryFormatter();
+            Stream stream = new MemoryStream();
+            using (stream)
+            {
+                formatter.Serialize(stream, source);
+                stream.Seek(0, SeekOrigin.Begin);
+                return (T)formatter.Deserialize(stream);
+            }
+        }
+    }
 }
diff --git a/HandsetDetectionAPI/HDDevice.cs b/HandsetDetectionAPI/HDDevice.cs
index 83717def..7a0946d1 100644
--- a/HandsetDetectionAPI/HDDevice.cs
+++ b/HandsetDetectionAPI/HDDevice.cs
@@ -318,7 +318,7 @@ public Dictionary<string, dynamic> FindRating(string deviceId, Dictionary<string
         /// <param name="specsField">string specsField : Either "platform', 'browser', 'language'</param>
         /// <param name="device"></param>
         /// <param name="specs"></param>
-        public void SpecsOverlay(string specsField, ref  dynamic device, Dictionary<string, dynamic> specs)
+        public Dictionary<string, dynamic> SpecsOverlay(string specsField, Dictionary<string, dynamic> device, Dictionary<string, dynamic> specs)
         {
             switch (specsField)
             {
@@ -361,6 +361,7 @@ public void SpecsOverlay(string specsField, ref  dynamic device, Dictionary<stri
                         }
                     } break;
             }
+            return device;
         }
 
         /// <summary>
@@ -406,11 +407,12 @@ private Dictionary<string, dynamic> InfoStringToArray(string hardwareInfo)
         /// </summary>
         /// <param name="device"></param>
         /// <param name="infoArray"></param>
-        private void HardwareInfoOverlay(ref dynamic device, Dictionary<string, dynamic> infoArray)
+        private Dictionary<string, dynamic> HardwareInfoOverlay(Dictionary<string, dynamic> device, Dictionary<string, dynamic> infoArray)
         {
             device["Device"]["hd_ops"]["display_x"] = infoArray["display_x"];
             device["Device"]["hd_ops"]["display_y"] = infoArray["display_y"];
             device["Device"]["hd_ops"]["display_pixel_ratio"] = infoArray["display_pixel_ratio"];
+            return device;
         }
 
         /// <summary>
@@ -425,7 +427,7 @@ private void HardwareInfoOverlay(ref dynamic device, Dictionary<string, dynamic>
         /// </summary>
         /// <param name="headers"></param>
         /// <returns>array The matched device or null if not found</returns>
-        private dynamic MatchDevice(Dictionary<string, dynamic> headers)
+        private Dictionary<string, dynamic> MatchDevice(Dictionary<string, dynamic> headers)
         {
             // Opera mini sometimes puts the vendor # model in the header - nice! ... sometimes it puts ? # ? in as well
             if (headers.ContainsKey("x-operamini-phone") && headers["x-operamini-phone"].ToString() != "? # ?")
@@ -494,7 +496,7 @@ private dynamic MatchDevice(Dictionary<string, dynamic> headers)
                 return this.FindById(itemid);
             }
 
-            return false;
+            return null;
         }
 
         /// <summary>
@@ -558,7 +560,9 @@ public dynamic V4MatchBuildInfo(Dictionary<string, dynamic> buildInfo)
             // Platform Detection
             dynamic platform = V4MatchBiHelper(buildInfo, "platform");
             if (platform != null && platform.Count != 0)
-                this.SpecsOverlay("platform", ref device, platform["Extra"]);
+            {
+                device = this.SpecsOverlay("platform", device, platform["Extra"]);
+            }
 
             Reply["hd_specs"] = device["Device"]["hd_specs"];
             return SetError(0, "OK");
@@ -695,9 +699,9 @@ private dynamic V4MatchHttpHeaders(Dictionary<string, dynamic> headers, string h
                 }
             }
 
-            dynamic device = MatchDevice(deviceHeaders);
+            Dictionary<string, dynamic> device = MatchDevice(deviceHeaders);
 
-            if (device is bool)
+            if (device == null)
             {
                 return SetError(301, "Not Found");
             }
@@ -715,7 +719,7 @@ private dynamic V4MatchHttpHeaders(Dictionary<string, dynamic> headers, string h
                 {
                     if (hwProps is IDictionary)
                     {
-                        HardwareInfoOverlay(ref device, (Dictionary<string, dynamic>)hwProps);
+                        device = HardwareInfoOverlay(device, (Dictionary<string, dynamic>)hwProps);
                     }
 
                 }
@@ -725,10 +729,10 @@ private dynamic V4MatchHttpHeaders(Dictionary<string, dynamic> headers, string h
             }
             // Get extra info
 
-            dynamic platform = _extra.MatchExtra("platform", extraHeaders);
-            dynamic browser = _extra.MatchExtra("browser", extraHeaders);
-            dynamic app = _extra.MatchExtra("app", extraHeaders);
-            dynamic language = _extra.MatchLanguage(extraHeaders);
+            Dictionary<string, dynamic> platform = _extra.MatchExtra("platform", extraHeaders);
+            Dictionary<string, dynamic> browser = _extra.MatchExtra("browser", extraHeaders);
+            Dictionary<string, dynamic> app = _extra.MatchExtra("app", extraHeaders);
+            Dictionary<string, dynamic> language = _extra.MatchLanguage(extraHeaders);
 
             // Find out if there is any contention on the detected rule.
             dynamic deviceList = GetHighAccuracyCandidates();
@@ -737,14 +741,14 @@ private dynamic V4MatchHttpHeaders(Dictionary<string, dynamic> headers, string h
             {
                 List<string> pass1List = new List<string>();
                 // Resolve contention with OS check
-                if (!(platform is bool))
+                if (platform != null)
                 {
                     _extra.Set(platform);
 
 
                     foreach (dynamic item in deviceList)
                     {
-                        dynamic tryDevice = this.FindById(item);
+                        Dictionary<string, dynamic> tryDevice = this.FindById(item);
 
                         if (_extra.VerifyPlatform(tryDevice["Device"]["hd_specs"]))
                         {
@@ -772,7 +776,7 @@ private dynamic V4MatchHttpHeaders(Dictionary<string, dynamic> headers, string h
                     // Sort the results
                     //usort($result, array($this, 'hd_sortByScore'));
                     Dictionary<string, dynamic> bestRatedDevice = GetDeviceFromRatingResult(result);
-                    dynamic objDevice = this.FindById(bestRatedDevice["_id"]);
+                    Dictionary<string, dynamic> objDevice = this.FindById(bestRatedDevice["_id"]);
                     if (objDevice.Count > 0)
                     {
                         device = objDevice;
@@ -782,25 +786,27 @@ private dynamic V4MatchHttpHeaders(Dictionary<string, dynamic> headers, string h
             }
 
             // Overlay specs
-            if (!(platform is bool))
+            if (platform != null)
             {
-                SpecsOverlay("platform", ref device, platform["Extra"]);
+                device = SpecsOverlay("platform", device, platform["Extra"]);
             }
-            if (!(browser is bool))
+            if (browser != null)
             {
-                SpecsOverlay("browser", ref device, browser["Extra"]);
+                device = SpecsOverlay("browser", device, browser["Extra"]);
             }
-            if (!(app is bool))
+            if (app != null)
             {
-                SpecsOverlay("app", ref device, app["Extra"]);
+                device = SpecsOverlay("app", device, app["Extra"]);
             }
-            if (!(language is bool))
+            if (language != null)
             {
-                SpecsOverlay("language", ref device, language["Extra"]);
+                device = SpecsOverlay("language", device, language["Extra"]);
             }
             // Overlay hardware info result if required
             if (device["Device"]["hd_ops"]["overlay_result_specs"].ToString() == "1" && !string.IsNullOrEmpty(hardwareInfo))
-                HardwareInfoOverlay(ref device, hwProps);
+            {
+                device = HardwareInfoOverlay(device, hwProps);
+            }
 
             Reply["hd_specs"] = device["Device"]["hd_specs"];
             return SetError(0, "OK");//for meantime
diff --git a/HandsetDetectionAPI/HDExtra.cs b/HandsetDetectionAPI/HDExtra.cs
index 30a6a1f2..243a14af 100644
--- a/HandsetDetectionAPI/HDExtra.cs
+++ b/HandsetDetectionAPI/HDExtra.cs
@@ -51,7 +51,7 @@ public dynamic MatchExtra(string className, Dictionary<string, dynamic> headers)
                     return extra;
                 }
             }
-            return false;
+            return null;
 
         }
 
@@ -71,7 +71,7 @@ public dynamic FindById(string id)
         /// </summary>
         /// <param name="headers">headers A key => value array of sanitized http headers</param>
         /// <returns>array Extra on success, false otherwise</returns>
-        public dynamic MatchLanguage(Dictionary<string, dynamic> headers)
+        public Dictionary<string, dynamic> MatchLanguage(Dictionary<string, dynamic> headers)
         {
             Dictionary<string, dynamic> extra = new Dictionary<string, dynamic>();
             // Mock up a fake Extra for merge into detection reply.
diff --git a/HandsetDetectionAPI/HDStore.cs b/HandsetDetectionAPI/HDStore.cs
index b878791c..f8e45564 100644
--- a/HandsetDetectionAPI/HDStore.cs
+++ b/HandsetDetectionAPI/HDStore.cs
@@ -130,7 +130,7 @@ public bool store(string key, Dictionary<string, dynamic> data)
         /// <returns> boolean true on success, false</returns>
         public T Read<T>(string key)
         {
-            var reply = _cache.Read<T>(key);
+            T reply = _cache.Read<T>(key);
             if (reply != null)
                 return reply;
 
@@ -138,7 +138,7 @@ public T Read<T>(string key)
             if (reply != null)
             {
                 _cache.Write(key, reply);
-                return reply;
+                return reply.Clone();
             }
             else
             {