The Gun is a spring loaded device that 'drives' the plug into the hole. The shaft of the plug expands under pressure to fill the puncture. The mushroom head of the plug seats on the inner wall allowing no air to escape. This insures maximum reliability from its' revolutionary design. The vinyl zippered pouch measures 6 1/2" x 9" x 1" and weighs 1 lb. 14 oz. It's easily stored - so you're always prepared.