A holder for TSO Track Saw Parallel Guides - two required for each guide rail. Designed to be mounted on the wall. The red knob can be turned to remove or secure the guides. The hole for the knob is threaded at 10-24 UNC. Instead of using a machine screw, I used a similar sized sheet metal screw to fasten the knob so that it rotates, but does not rotate the sheet metal screw (the correct sized machine screw does rotate freely, so was a poor design choice).