This is a set of 85°, Main, 3/8" Robostrut ready, Robart 511RS Retracts with Air Kit. FEATURES: The 510 Series Retract offers a high performance air up and spring down Set up from the factory to accept 3/8" Robostruts (ROBQ1700) Complete air kit designed for the 510 Series Retracts The 510 Series Economy Retracts are designed to replace other manufacturers" Retract systems INCLUDES: 511RS Retracts Air kit: -Very small air tank, ROBQ2380 -Control Valve -Fill Valve -Air Supply in fitting -Three tee fittings -Orange air line Instruction sheet REQUIRES: Robostrut (ROBQ1700) Air pump (ROBQ2363) Servo Round servo horn (Servo wheel) Link rod assembly to the Control Valve SPECS: Retract Unit: Length: 3-5/8" (including air cylinders) Width: 1-3/4" Depth: 1-1/8" Robostrut mounting size: 3/8" ajw 7-28-05 ir/jxs updt jxs 09/07/10