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 materials from ½" to 1½" thick. The Material Thickness Gauge allows you to easily determine material thickness, and has markings for ½", ¾", and 1½" material ranges. 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.