IPS-Twin Power System Weight: 42 grams / 1.50 oz. Gear ratio: 87T / 9T = 9.7 Recommended battery is 4.8V (2/3 AA 270 to 600 mAh). Using higher than 4.8 Volts will greatly decrease the lifetime of each motor. Using two heat sinks will extend both motor lifetimes. CAUTION: Using a larger than recommended propeller and/or higher voltage battery may cause permanent damage to this motor. Recommended Propellers: 13 x 6 1/2, 13 x 9, 14 x 7, 14 x 10 Recommended Batteries: 2 or 3 NiMH-AAA 1.2V - 600mAh, NiCAD 4.8V - 110mah NiCAD 4.8V - 150mah