FUNCTION - Internal centering pin locates center of dowel for accurate drilling.CHROME PLATED - will not to mark wood, Used for locating according to corresponding hole.WIDE APPLICATION - works with both standard and brad-point bits, For use on twist drill bits or brad point drills to prevent excessive drill bit penetration.Color: silver + black8x Dowel and Tenon Pins:Specification:Material: steelColor:silverSurface treatment: chromeplateSize: 1/4 inch 5/16 inch 3/8 inch 1/2 inchQuantity: 8pcs (2pcs per size)8x Drill Stop:Specification:Material: carbon steelSizes: 1/8,3/16,1/4,5/16,3/8,7/16,1/2,5/8 inchThickness: 35mmHeight: 8mmChrome plated so as not to mark wood.Connects dowel to block, then cover the dower by another block.For accurate alignment of drill holes when dowel-pinning joinery.Using drill bit to align with the round imprinted to make two blocks join perfectly.Come with hex wrench.Setscrew type collar will not damage bits.Works with both standard and brad-point bitsCompatible with any twist type bit for wood metal concrete or masonry with hex set screws.Mainly for fixing the drill bit,limited the depth of drill holes,make depth of the hole .Package includes:8x Dowel Centers8x Drill Chuck1x Hex WrenchOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.