This is the HS-322HD Standard Heavy Duty Servo from Hitec. The HS-322HD Standard Heavy Duty Servo utilizes Hitec’s revolutionary Karbonite™ gear train which is four times stronger than Hitec's standard white nylon gears, and even after hundreds of thousands of cycles they don’t show any signs of wear. Karbonite™ gears and Hitec's custom IC makes the HS-322HD a great choice for an economical sport servo.