Compatible with Hitec Parallax Futaba MG995 MG996R Servos,also can fit for other brands standard servos (size 40x20x36mm). Widely used on RC models airplane, RC helicopter, RC car, RC Boat, Robot and so on. Made of aluminum alloy material,durable in use. Diameter: Approx. 24.5mm;Mounting Hole Spacing: Approx.16.5mm