First Watch Security 1110-SN is a night bolt that provides an additional layer of security to your doors. It features a cylinder lock with two connecting screws, a connecting bar, and a strike plate. The lock can be installed on doors with a thickness of up to 2-3/8 inches and requires a 1-1/4 inch diameter hole for the cylinder. The connecting bar can be adjusted to fit different door thicknesses and should protrude 3/8 inches beyond the inside of the door. The strike plate should be installed on the door jamb lower than the centerline of the lock to allow for any door sag.