The General Tools S838 6 Pieces Drill Stop Set. Drill stops are used to prevent excessive bit penetration in doweling and other drilling applications. Attaching a Drill Stop to the twist or brad-point drill bit assures that hole is drilled to the specified depth. The General S838 Drill Stop Set includes six, cold-rolled steel Drill Stops in a black oxide finish. The Stops attach easily to standard drill bits with a set screw and hex wrench (included). The set also includes a reusable snap blister for storage.