Hirobo HI2500047 12 x 21 x 5 mm Shielded Ball Bearings, 2 pcs  [HI2500047]

12 x 21 x 5 mm bearings for model hobbyists

This product is a set of two Hirobo shielded ball bearings, 12 x 21 x 5 mm, supplied as 2 pcs for hobby model use. They are suitable as replacement bearings where space is limited and reliable rotation is required.

The shielded steel design helps reduce friction while offering some protection against contaminants. Typical uses include small drive shafts, tail assemblies and gearbox bearings where the 12 mm ID and 21 mm OD correspond to the host parts. Always confirm measurements prior to fitting.

Installation advice: press the bearing in using even pressure on the outer race or a driver sized for the 21 mm outer diameter to avoid stressing the inner race. If removal is needed, use a bearing puller or apply controlled heat to the housing to ease a tight press fit, rather than levering directly on the bearing faces.

Service notes: clear debris from the seating area before installation, consider a light, hobby-grade lubricant only if compatible with the shielded construction, and inspect shields for any damage. Smooth bearings help reduce drive train vibration and improve precision.

Storage and replacement guidance: store bearings in a dry, dust-free place and replace them when you detect rough operation, excessive play, or unusual noise under load. Periodic checks after heavy operation are recommended.