The metal D-645MW is part of Hitec's D-Series dynamo servo line. All Hitec D-Series servos have been designed using their cutting edge, custom engineering. Combining industry leading high-resolution, state-of-the-art ultra-response technology with a 32-bit MCU and 12-bit ADC for unprecedented programmability and flexibility, these servos deliver significantly smoother movement. The speedy, powerful line operates on a wide 4.8 ~ 8.4 voltage range, allowing use with any common battery chemistry without the need for adapters or regulators. Featuring Hitec's industry standard 25-tooth output spline with 3mm hex screw, each D-Series servo brings monster performance never known before in the market. - Motor Type: Coreless - Bearing Type: Dual Ball Bearing - Speed (4.8V / 6.0V / 7.4V): 0.28 / 0.20 / 0.17 sec/60 - Torque oz-in (4.8V / 6.0V / 7.4V): 115 / 158 / 180 oz-in - Torque kg-cm (4.8V / 6.0V / 7.4V): 8.3 / 11.4 / 13.0 kg-cm - Size in Inches: 1.59 x 0.77 x 1.48 in