Hirobo HI2521091 Collar 5 x 7 x 18.3 Precision Spacer  [HI2521091]

Precision Collar for RC Helicopters

This RC-scale collar is supplied as a spare or replacement part for model helicopters and is listed under Hirobo model HI2521091. The dimensional callout 5 x 7 x 18.3 is the key specification used to confirm shaft fit and axial spacing in tight rotorlinkage and transmission layouts.

The collar serves as a mechanical spacer and locating feature inside rotor linkages or component stacks, helping to keep mating parts aligned and permitting small axial adjustments where accurate positioning is important.

Fitting notes are general: check the 5 x 7 x 18.3 dimension against your model shaft or bore, slide the collar into place where required by the assembly, and secure it using your model’s existing fasteners and procedures. This item is offered strictly as an RC accessory and is not intended for full-scale use.