This 3D model was originally created with Sketchup 13 and then converted to all other 3D formats. Native format is .skp 3dsmax scene is 3ds Max 2016 version, rendered with Vray 3.00 Toothed washer, with countersunk screw holes to fix down, grooved %26 drilled to take tension spring - pairs work together on a quick-release axle for easy adjustment %26 robust locked tight strength.