These are NON-Rotating 85° or 90° Micro Main Gear Retracts by Robart. They are Designed for Small Gas and Electric Powered Models. This Retract System is Mechanical. FEATURES: Retract Gears made of Tough Nylon Construction and Gear Legs made of Tempered Steel. Positive Down Lock locks the Gears for Safer Landings. INCLUDES: Two Main Landing Gears Eight 3/16x7/16" S/T Screws One 1/32" Allen Wrench One Instruction Sheet SPECS: Weight: 0.9oz per pair (not including wheels and collars) Weight Range: Up to 2lb (907g) capacity Gear Leg Diameter: 3/32" Distance between mounting holes: 1-5/16" long, 11/16" wide Servo Travel: 5/8" Strut Wire Diameter: 3/32" Length of Gear: 1-5/8" (41.3mm) Width of Gear: 29/32 (22.9mm) REQUIRES: Mini or Standard Servos (depending on radio system and application) Wheel Collars (GPMQ4302) Epoxy Resin (GPMR6045) Fiberglass Cloth (GPMR1054) for wheel wells wheels (size depends on application) 1/16" Music Wire COMMENTS: This is not for use with micro servos. mgc 7/22/97 ir/jl updt jxs 1/17/06