The Align Trex 500 Pro 145 Tooth, Mod 0.6 Autorotation Tail Drive Gear is a replacement component for the Align T-Rex 500 Pro radio-controlled helicopter. The tail drive gear is responsible for driving the tail rotor, which is crucial for maintaining stability and control during flight. The modulus of 0.6 refers to the pitch of the gear teeth, which affects the speed at which the tail rotor rotates. The 145 tooth count is specific to the Align T-Rex 500 Pro helicopter. This replacement gear has a weight of 24.1g and comes in black color. It is made from durable materials and is designed to withstand the demands of high-performance RC helicopters. This package includes one autorotation tail drive gear.