A6390 Mid-Torque Mid-Speed Standard ServoOverview The Spektrum A6390 standard size analog sport servo is the perfect budget solution that offers a lightweight plastic gear train, a budget class leading torque rating of 66 oz in and quick transit speed of 0. 14 60. Single ball bearing output shaft and a robust composite plastic case offers durability you can depend on in your 60 size or smaller trainer and sport models. Includes all the mounting hardware and 3 Heavy Duty plastic arms needed