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 a 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