WHITESIDE Special T-Slot Router Bits are designed to make easy work of creating your own professional woodworking jigs and fixtures. The Medium T-Slot measures 3/4" W and 3/16" H at the base with a 1/2" shank. It requires the cutting of a 3/8" straight groove prior to routing the “T”. Carbide tipped. 1/2" Shank Produces a slot size of 3/4" wide x 3/16" high. Requires 3/8" straight groove. Carbide tipped.