This kit includes the same Easy-Set Stop Collar and Material Thickness Gauge/Hex Wrench that come with Kreg® 300-Series 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 for 1/2", 3/4", and 1 1/2" materials. The Material Thickness Gauge allows you to easily determine material thickness (1/2", 3/4", 1 1/2"), and has a built-in hex wrench for tightening the stop collar. Collar also fits all other standard (3/8"-diameter) Kreg pocket-hole drill bits.