This kit includes the same Easy-Set Stop Collar and Material Thickness Gauge/Hex Wrench that come with Kreg® 300-Series Pocket-Hole Jigs. Easy-Set Stop Collar features a window that aligns with the engraved markings on the Kreg Easy-Set Pocket-Hole Drill Bit (sold separately). The Material Thickness Gauge allows you to easily determine material thickness from 1/2" to 1-1/2", and has a built-in hex wrench for tightening the stop collar.