National Marker N350850 Spring Door Hinge Oil Rubbed Bronze

Product Description

The NATIONAL MARKER N350850 is a 4-inch spring door hinge finished in oil rubbed bronze, designed to automatically close doors after each use. Part of the V521 series, it is built from cold-rolled steel and features a 1/4-inch corner radius that fits standard hinge cutouts without modification. The closing speed is field-adjustable, giving installers control over door swing behavior. This hinge carries UL approval for use on fire-rated doors, making it suitable for code-compliant installations in a wide range of building types. Carpenters, finish contractors, and general tradespeople are the typical installers.

The N350850 is suited for residential, commercial, and apartment building applications. Common install locations include basement access doors, stairway doors, garage entry doors, and building entrances where self-closing function is required by fire code or building policy. The adjustable closing mechanism makes it practical for high-traffic openings where door speed may need periodic tuning.

Key Features

• Self-closing spring mechanism with adjustable closing speed
• UL approved for fire-rated door applications
• Cold-rolled steel construction for durability
• 1/4-inch radius corners fit standard hinge cutouts
• Oil rubbed bronze finish for corrosion resistance and appearance
• Suitable for residential, commercial, and multi-unit residential buildings

Compatibility

Designed as an OEM-style replacement and new-installation spring hinge for standard door hinge cutouts on self-closing interior and exterior doors in residential and commercial construction.

Installation Notes

Installation is performed by a carpenter or licensed contractor. Shut off any automatic door hardware or electronic access control tied to the door before removing existing hardware. Use a standard hinge template and chisels to confirm the mortise matches the 1/4-inch radius corner profile before fastening. Consult local fire and building codes, including IBC and NFPA 80, when installing on fire-rated door assemblies to ensure full code compliance.