Hirobo HI2521125 Precision Collar 3 x 4-6 x 15.5 for Helicopter Shafts  [HI2521125]

Alignment collar for small-scale helicopters

This collar fits RC helicopter builds where a 3 x 4-6 x 15.5 item is required, acting as a spacer and axial locator in tight assemblies. It helps secure the relative position of rotor and transmission components to preserve intended geometry.

Fitting method depends on the host model's hardware; in most cases the collar slides over the shaft and is held by the existing clamp or screw. Before final assembly, double-check shaft diameter and mating fit to avoid any free play that could degrade rotor balance or drive smoothness.

Use the collar for tuning to establish accurate axial clearance and to return gears, hubs, or linkages to a known position during rebuilds. It provides a repeatable mechanical reference that supports consistent pitch and tracking adjustments at the field.