Original Makita O‑Ring 21 — part 213381-5. This is an original Makita rubber sealing O‑ring marked “21” (nominal 21 mm size) used to maintain airtight/grease seals inside SDS‑Plus rotary hammer assemblies.
The ring is a small rubber sealing gasket that sits in the impact/gear area to stop grease loss and keep the piston/bit mechanism running smoothly; it’s the same style of seal used across Makita rotary hammers.
Example models that use this part include HR2300, HR2600, HR2610 / HR2610T, HR2611F (and HR2611FT), HR3510/20, HR3520, BHR242, BHR243 and related DHR/BHR series rotary hammers — check the exploded parts list for your model to confirm placement.
Supplied as the single O‑ring (qty 1 on the Makita parts list), it’s a simple, low-cost replacement that restores the seal integrity of the tool without other changes. Keep this genuine Makita spare with your Makita parts so you’ve got the right power tool parts when a seal needs replacing.
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