These hold-down clamps are perfect when you need to secure work pieces on router table, drill presses or other machines. The 1/4" x 20 TPI hex head bolts that come packaged are compatible with most T-Track brands. The rubber tips on each end are non-marring and help to securely grip work pieces. They are made from solid anodized aluminum, are 5-1/2" long, 1" wide and 1/4" thick allowing for substantial tension to be exerted. Comes with two (2) 1/4" x 20 TPI x 3" long hex head bolts and two (2) 3" T knobs.