The Wilton Model R-Rubber Face Magnefix Jaw Caps for Bench Vises are constructed of aluminum alloy with a synthetic rubber cover. The jaw cap conforms to the workpiece and firmly grips without marring the work surface. The caps can be used in combination with aluminum and prism jaw caps to clamp taper pins or tapered workpieces. ADDITIONAL SPECIFICATIONS: Model No.:R-4; Jaw Width: 4"