For use with Kreg pocket hole Jigs, these blocks are great for quick and easy repair work. Features: * Each spacer compensates for 1/4-inch in material thickness * Simply add the blocks to the bottom of the Jig"s Drill Guide * Use one block for 3/4-inch material, 2 for 1-inch material and 3 for 1-1/4-inch material. Includes 3 blocks. * Compatible with all versions of the Kreg Jig (model K4), and all versions of the Kreg Jig Master System (model K3MS) sold on or after 11/1/2008, featuring Spacer Block slots on the underside of the Drill Guide What"s In The Box: * Kreg KDGADAPT Drill Guide Spacer Blocks