Yost Vises MR-340 4" Magnetic Aluminum Vise Jaw Caps with Rubber Finish (1 Pair) Jaw caps attach to and cover a set of 4"-wide serrated vise jaws to shield delicate work from damage Aluminum provides durability, and the rubber finish prevents the clamped item from being marred Magnetic backing runs the full length of the cap to securely bond it to the vise jaw