Key Features: Robust landing gear strut and mounting bracket Integrated electric motor with a micro PCB Built-in over-current protection Aircraft weight: 2.00–4.50 lb (0.90–2.00 kg) Strut diameter 0.118 in (3mm) Strut length 0.866 in (22mm) : Overview: You don't have to be a master modeler to add the realism of functioning retracts to your airplane. The completely self-contained E-flite retract system requires no air tank, complex linkages or extra servo. It can simply be bolted into place and plugged into the receiver. A specially-designed Y-harness is included that allows for the use of a single receiver channel to control all retract units. Detailed Information: 10-15 Size Main Retract Units (mm)