Hirobo HI2521146 collar 7 x 8 x 4 RC helicopter retention collar  [HI2521146]

RC helicopter retention collar

This Hirobo collar is an RC-scale retention part identified by the HI2521146 code and the 7 x 8 x 4 sizing in the product name. It serves as a small axial clamp used where a compact collar is needed to hold shafts, linkages, or sliding assemblies in place inside model helicopters and similar RC components.

Designed as a straightforward replacement item, the collar's primary role is positional retention rather than load bearing. In practice it helps keep cyclic linkages, tail shafts, or intermediate studs from shifting under vibration or during setup and tuning. Confirm the collar's 7 x 8 x 4 dimension matches the shaft and bore of your assembly before fitting.

Installation notes: clean mating surfaces to remove burrs or debris, slide the collar into position and verify axial seating and free rotation where required, inspect regularly for wear and replace if the fit loosens. The part is presented as a swap-in accessory for routine maintenance and tuning tasks on RC helicopters.