Technical divers who use aluminum or stainless steel back-plates have a need for attachment of accessory items. Most back-plates have holes on them specifically for this purpose. Book Screws are used to anchor the accessory in place to keep them secure and close at hand. The Zeagle Two Piece Plastic Screw Fasteners are a must have spare for any technical diver. If you're fastening a bladder to a back plate, accessory items like a Zeagle Universal Mount. Zeagle Surface Marker Buoy QD Deluxe Signal Tubes, Zeagle E-Z Mount QD Pouch for Signal Tube and more. Two Piece Plastic Screws have multiple uses and should be a standard spare in any technical or sport diver's save-a-dive-kit.