Genuine DeWalt O‑Ring — part #174055. Precision sealing O‑ring (approx. 44.7 mm OD x 3.5 mm cross‑section) designed to restore airtight performance in DeWalt coil and connector nailers.

Built for the piston/head sealing chamber, this original DeWalt replacement ring prevents air leaks, preserves firing power and consistency, and is supplied as the direct-fit seal used on models such as DPN250MCN, DPN64C‑1/DPN64‑1 series, DPN75C and compatible DWMC150 / DW66C‑1 nailers.

Features:

- Part number: 174055 (DeWalt).

- Size: ~44.7 mm diameter x 3.5 mm thickness — exact fit for the piston head seal.

- Purpose: restores proper air seal and tool performance; recommended when pistoning action shows air loss or reduced power.

Quick, inexpensive maintenance part that gets your nailer back to factory sealing specs — install where the piston head/valve seals to prevent misfires and inconsistent driving depth.