Spend enough time with a CNC machine and mistakes are bound to happen. Whether something goes wrong with the toolpath, or you place a clamp in the path of the router bit, the result is that both clamp and bit are ruined. These clamps are designed to minimize damage in the event that that happens. They feature the same functionality as our standard Hold Down Clamps, but are made of a polymer material with aluminum threads, making them far less likely to damage your expensive router bits. In addition to use with CNC machines, the clamps are also great for T-track tables and shop-made jigs, where contact with router bits and cutters is also possible. Features: Components made from materials that wont damage cutters in the event of accidental contact -- great for CNC use!Glass-filled ABS clamp arms with non-marring rubber tips hold workpieces securely without crushing fibers5/16-18 x 3 T-Bolts and inserts are made from softer aluminum, rather than the usual steelUse with tables and jigs incorporating standard T-TrackClamps material up to 2-1/2 thick