This is a Set of 90° Non-Rotating Heavy Duty Retracts for Model Airplanes weighing 5-10 Pounds. FEATURES: Heavy duty struts, 3/16" diameter wire The Robostruts will NOT directly fit these struts (the bushing that comes with the Robostruts, ROBQ1700 - ROBQ1706, can be drilled out to 3/16" to make them fit). Positive up and down lock and smooth cam action mechanism. Glass-filled nylon housing supports an aluminum pivot bearing. INCLUDES: One 90° Heavy Duty Retract Unit Right Side One 90° Heavy Duty Retract Unit Left Side Eight Mounting Screws One Detailed Installation Instruction Sheet SPECS: Retract Unit: Length: 3.69 (including air cylinder) Width: 1.75" Depth: 1.125" Struts: Length: 7.75" Diameter: 3/16" Weight (per pair): 6 oz. REQUIRES: Air Control Kit (tubing, valves, air vessel). Hand Pump with Gauge, use ROBQ2363 Wheels. 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)