Abstract: A kit for assisting in the location of holes to be drilled in a door of a thickness between 1?? to 1¾? for the installation of a conventional lock set at a backset of either 2?? or 2¾? with no additional hardware and without damaging the door. A first guide plate defines a first hole saw guide. A second guide plate is attachable to the first guide plate in one of two orientations and defines a second hole saw guide. At least one clamping member is carried by the second guide plate and extends substantially parallel to the first guide plate. Each of the first guide plate and the clamping member define opposing biasing members such that when mounted on a door, the door is centered within the kit.