This is a set of two (2) Robostrut Ready 85?? Retracts for planes 10-14lbs These are for the Main Gear only. INCLUDES: Two Retracts with Pressure Cylinders Two Collars for fitting of Robotruts One instruction sheet REQUIRES: Installation of air system SPECS: Length: 3.75" total length Width: 1.75" at the base Height: 1.2" total from bottom of mounts to top of unit COMMENTS: Do not supply more than 125 psi to any part of the Retract system. RobartPart ROB531RS