This kit includes the same Easy-Set Stop Collar and Material Thickness Gauge/Hex Wrench that come with the Kreg 310 and 320 Pocket-Hole Jigs. The collar features a window that aligns with the engraved markings on the Kreg Easy-Set Pocket-Hole Drill Bit to make setting the bit at the correct depth easy. The Material Thickness Gauge allows you to easily determine material thickness, and has markings for 1/2'', 3/4'', and 1-1/2'' thicknesses. A built-in hex wrench works to tighten the stop collar. Collar also fits all other standard (3/8'' diameter) Kreg pocket-hole drill bits.