Genuine Makita 318303-1 Bearing Box Cover — direct replacement cover that protects and supports the lower bearing and bearing assembly on 5" random-orbit sanders, keeping the spindle aligned and helping reduce vibration during use.

The part is a precisely made metal cover (die‑cast style, factory‑machined surfaces) that seals the bearing area against dust, grit and impact — restoring the original fit and tolerance your tool needs for smooth pad rotation.

Compatible with Makita 5" random-orbit models such as BO5030, BO5031, BO5041 (and related 125 mm class sanders), and is listed individually as part number 318303-1 in Makita parts catalogs.

Easy to install during a routine bearing service — the cover is sold individually and typically installs with a screwdriver and small nose pliers to secure and route any retaining tabs or seals, so you can get the sander back to spec quickly.