Use with Silicone Sealant Mastic Caulk and Adhesive cartridges These skeleton guns can be used with standard 310ml cartridges. They are lightweight and made from strong steel so comfortable for long periods of use and can take a bit of punishment. Much thought has gone into the design of this 12 Post Port Letterbox from its telescopic sleeve which provides a perfect fit to its flap that can open up to 180 for easier posting. Features & Benefits Skeleton Gun Fits standard 310ml & 400 ml EU3 cartridges Strong and lightweight steel frame and trigger Quality Design comfortable ergonomic sprung trigger Sprung Thumb Plate lockunlocks plunger and releases pressure