This is a Set of 90° Non-Rotating Main Retracts for model airplanes weighing 8-18 Pounds. FEATURES: These are Robostrut Ready Positive up and down lock and smooth cam action mechanism. Glass-filled nylon housing supports an aluminum pivot bearing. Retract Unit Only with NO Struts INCLUDES: One 90° Heavy Duty Retract Unit Right Side One 90° Heavy Duty Retract Unit Left Side One Detailed Installation Instruction Sheet REQUIRES: Air Control Kit (Tubing, Valves, Air Vessel). Hand Pump with Gauge, use ROBQ2363. Wheels, Struts. SPECS: Retract Unit: Length: 3.69" (including air cylinder) Length: 1.5" (Mounting plate) Width: 1.75" Depth: 1.125" COMMENTS: Optional Quick Connector (ROBQ2395) (for ease in connecting and disconnecting the lines to the wings) Optional Air Restrictors (ROBQ2389) (restricts air flow to the Retract for a realistic movement, and slows down the Retract mechanism to scale speed). A standard servo may be used to operate these Retracts. Axles are Not Included (The instructions state how to bend the struts with heat) jmm 5/4/02 ir/kh