Features The gear is made of cast steel and offers higher strength, durability and wear resistance. Transfer the torsion of your servo into a gear with these MOD 0.8 servo drives. This 20 tooth servo gear is most commonly used to drive the 100 tooth hub gear at a distance of 48mm to achieve a 5:1 gear ratio. This reduction increases the torsion on the hub gear to five times what the servo produces. With 25 teeth MOD 0.8, easy to install and use, long service life. Specification: Item type: servo gear Material: cast steel. Product Model: 4307-1025-0020 Product specification: 20-tooth power steering gearbox (25-tooth spline MOD 0.8) Pitch diameter: approx. 16 mm / 0.63 inches. Outer diameter: approx. 17.6 mm / 0.69 inches. Package list: 1 x gear wheel Package List 1 x Gear