This is the stepped bit and depth collar set supplied with Kreg 300-series pocket-hole jigs, available on its own as an upgrade to any older-model Kreg pocket-hole jigs that use a 3/8" bit (i.e., not for use with heavy-duty or micro-pocket guides).
To help make depth settings easy and accurate, simply align the hole in the depth collar with engraved markings on the shank, which indicate the correct settings for 1/2", 3/4" and 1 1/2" thick material. The 6 1/4" long HSS bit has a 3/16" diameter by 1/2" long pilot, a 3/8" diameter counterbore, and a 1/4" hex shank that’s grooved for use in quick-change chucks.
Material-thickness gauge also included. Made in USA.