All HVS series servos are designed primarily to exploit the advantages of high voltage (7.2v) & the benefits that gives in both speed & torque. The HVS-ZS is the high speed version for cars yet can still deliver over 20kg/cm of torque. Please check that your receiver can handle 7.4v before using this servo at that voltage. Twin ball races with metal gears. Specification Weight: 63g Dimensions: 40.5 x 21 x 38mm Speed: 0.10 sec/60° (7.4v) Torque: 20.5 Kg/cm (7.4v) Manufacturer: Ripmax Model: P-SWDHVSZS