This is a Robart Robostrut Ready 90° Main Gear Set with Air Kit. FEATURES: The 510 Series Retract offers a high performance air up and spring down. Setup from the factory to accept 3/16" struts Main gear set designed for the 510 Series Retracts The 510 Series Economy Retracts are designed to replace other manufacturer"s Retract systems. INCLUDES: 510RS Main Retracts 3/16" landing gear wire Air kit: -Small air tank -Control valve -Fill valve -Air supply in fitting -Three tee fittings -Orange air line Instruction sheet REQUIRES: Air pump (ROBQ2363) Link rod assembly to the Control Valve SPECS: Main Retracts: Length: 3-5/8" (92.5mm) including air cylinders Width: 1-3/4" (44mm) Depth: 1-1/8" (28.5mm) Landing gear wire hole: 3/16" (5mm) COMMENTS: Order ROBQ0659 for Axle Adapter with 3/16" Axle ajw 8-9-05 ir/jxs updt jxs 05/03/10