This is the E/Z Brake System from DU-BRO.
Main or nose wheel R/C airplane braking system
Works with 5/32" (.156") and 4mm diameter landing gear with the
following DU-BRO wheels 2.25"-3.5" T, TL, SL, DL and R series
Useful in take-offs and landings where quick stops and tighter turns are needed
Adjustable tension so the brake can be on or off, or partial braking
set during taxing and turning
E/Z Brake System with Instructions