htc-vive-marker-mount Requires additionally the following material: 19x DIN 933 M2 10mm Screws with Nuts 5x DIN 562 M4 5x DIN 965 M4 Various Lengths for multiple VIVE HMD Tracking (min. 40 mm) 5x OptiTrack Marker: 15.9mm (5/8), M4 thread: Link