Exceptional customer value. Runs up to 33 hours on 2 alkaline 'D' cell batteries. Space saver clam shell package 3-7/8" x 7-1/2" x 2"D. Aerates up to 7-1/2 gallons. Pumps 7/8 liter of air/minute. Runs quietly on 1 or 2 'D' cell batteries. Adjustable stainless steel clip and fasteners. Individually tank tested. Weighted air stone. Beryllium copper battery contacts. Diaphragm pump. Fresh or salt water.