Model : 1501/50(50cc Aluminum) Model : 1501/100(100cc Aluminum) Model : 1503/50(50cc Stainless Steel) Model : 1503/100(100cc Stainless Steel) Model : 1501/CW(Counterpoise Weight) - ASTM D1475, DIN 53217, ISO 2811-1, BS3900 part A19