This is a 2-Way Air Control Valve for Most Pneumatic Retract Systems. FEATURES: Brass Air Line Pressure Fittings Double O-Ring Seals 2-56 Threaded Valve INCLUDES: One 2-Way Control Valve One Instruction Sheet for 2 and 3 Gear Installation REQUIRES: Servo, Servo Wheel, Linkage Rod w/Clevis, and Air Tubing COMMENTS: Valve has five pressure fittings. Two are used for "down" air line Two are used for "up" air line One goes to pressure vessel (air tank) and filler valve. This can mount to fuselage formers or any wood up to 1/8" thickness by using the pre-installed knurled nut. JAL 1/15/99 ir/jl