A bench dog is an accessory used on a woodworking workbench to allow clamping of wooden items while being worked or as a planing stop. Dog in general is something which holds. At its most basic a bench dog is simply a peg which is installed in a corresponding dog hole in the top of a bench. The holes are arranged in a line perpendicular to the vise, perhaps three or four inches apart but certainly no further apart than the fully open distance between the vise's jaws.