ESP KAB-44 Korrect-A-Bore lock installation tool. Used to enlarge, move or re-bore a misaligned cross bore lock hole in a door. Can also be used to change lock backsets from 2 3/8" to 2 3/4" or vice versa. Trues the cross bore hole for proper lock alignment. Steel tool attaches in the door using the mortised latch opening.