Marine Metal Products Big Bubbles Watertight Air Pump Precision motor runs 100 hours on 2 alkaline "D" cell batteries. Diaphragm pump. Will float if dropped overboard. Aluminum battery holders. Weighted glass bead airstone with 30" of air line tubing. Aerates up to 7-1/2 gallons. Pumps 7/8 liter of air/minute. Fresh Adjustable stainless steel clip and fasteners. Booted waterproof switch.