Makita HY00000408 — O‑ring 26.5 mm (original Makita)
Replace a worn seal quickly with this genuine Makita O‑ring (part number HY00000408). It’s the 26.5 mm sealing ring specified for Makita nailer assemblies and repair kits, sized for direct fit in the valve/cylinder sealing locations (26.5 mm nominal diameter).
Fits examples: Makita AF506 (18 g brad nailer) and AT638A (8‑bar narrow‑crown nailer) — the exact same 26.5 mm O‑ring used on those assemblies. If your tool is leaking air or the valve won’t hold pressure, this is the small replacement seal that commonly cures the problem.
Why this part matters: the ring is the factory‑specified seal used in the nailer’s internal valve/cylinder area, so installing the original Makita HY00000408 restores the intended sealing dimensions and fit. Keep this genuine Makita spare when repairing pneumatic nailers to get the correct fit for Makita parts without guesswork.
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