Hirobo HI2521111 Collar 5 x 7 x 13.2  [HI2521111]

Shaft alignment collar for small helicopters

The Hirobo HI2521111 collar is a compact accessory for RC helicopters, corresponding to the 5 x 7 x 13.2 sizing in the product title. It functions as a radial locator and retention ring on shafts and linkages where a small mechanical stop or spacer is needed.

Fitting is simple in common model workflows: the collar slides onto the shaft to set axial position, then is secured by the retention method used on your airframe (set screw, circlip, or adhesive as appropriate). When adjusting rotor play or linkage end float, apply the collar to establish repeatable limits and reduce axial movement that can affect trim.

Being lightweight and small, this collar is intended for maintenance and fine adjustments rather than carrying primary structural loads, and it fits into normal assembly and balancing procedures for small helicopters.