Hirobo HI2521104 COLLAR 3 X 6 X 12.5S - Helicopter collar part  [HI2521104]

Helicopter Collar 3×6×12.5S

This collar is an RC-scale helicopter replacement part sold under the Hirobo designation HI2521104. It serves as a compact fastener used where a low-profile collar is needed on shafts or linkages in helicopter assemblies. The product name includes the dimensional identifier 3 x 6 x 12.5S which defines the part's nominal size for matching existing shafts and housings.

For installation, inspect the mating shaft and bore for wear, remove debris, and slide the collar into position before securing it with the original retaining method present on your model. Because individual airframes vary, confirm fit and clearance before flight; small alignment differences can affect tail or rotor tracking on RC helicopters.

In tuning and maintenance use, collars like this are primarily for precise axial positioning and to prevent lateral play in rotating assemblies. Fitment checks during routine maintenance help keep rotor heads and tail assemblies running true, which supports predictable trim and handling on the model scale.