Hirobo HI2521125 Collar 3 x 4-6 x 15.5  [HI2521125]

Collar for RC helicopter assemblies

This is an RC-scale collar intended for helicopter general parts where a 3 x 4-6 x 15.5 collar is required. It functions as a spacing and alignment element in small mechanical assemblies, helping set axial position on shafts and maintain consistent spacing between components in the rotor or transmission area.

Installation depends on the host model's fastening method; the collar typically slides onto the shaft and is secured by the model's existing clamp or screw arrangement. When replacing or tuning, confirm shaft diameter and mating fit before final assembly to avoid play that can affect rotor balance or drive smoothness.

For tuning and maintenance, use the collar to fine‑tune axial clearance and to repeatably locate gears, hubs, or linkages during reassembly. Its role is to provide a stable mechanical reference so adjustments to pitch, tracking, or drive engagement remain consistent across field sessions.