National Mfg N350-777 Spring Door Hinge 3.5in Satin Nickel

Product Description

The NATIONAL MFG/SPECTRUM BRANDS HHI N350-777 is a 3.5-inch spring adjustable door hinge finished in satin nickel. Manufactured from cold rolled steel, it provides durable, consistent self-closing performance in residential and light commercial door applications. The closing speed and spring tension are both field-adjustable, allowing installers to fine-tune the hinge to door weight and traffic demands. The N350-777 carries UL approval for fire doors, making it a code-compliant choice where fire-rated assemblies are required. Square corners match standard hinge cutout geometry for straightforward drop-in installation. Sold in a package of two hinges.

This hinge is suited for interior and exterior doors in residential construction, multifamily housing, and light commercial settings where self-closing doors are required by code or building specification. It fits standard hinge cutouts, reducing the need for additional mortising or modification. The satin nickel finish complements common hardware finishes. Carpenters, finish contractors, and general contractors typically install this hinge during door hardware rough-in or finish trim stages. Its UL fire door listing makes it appropriate for stairwell doors, corridor doors, and other openings that require a rated self-closing assembly.

Key Features

• Adjustable closing speed for controlled, consistent self-closing action
• Adjustable spring tension to accommodate varying door weights
• Cold rolled steel construction for strength and durability
• UL approved for fire door applications
• Square corners fit standard hinge cutouts without modification
• Satin nickel finish for corrosion resistance and clean appearance

Compatibility

Designed as an OEM-style replacement or new-installation spring hinge for standard residential and light commercial door assemblies requiring a 3.5-inch square-corner hinge cutout.

Installation Notes

Installation is typically performed by a carpenter or finish contractor using standard hand tools. Verify the door frame mortise dimensions match the 3.5-inch square-corner profile before installation. When installing on a fire-rated door assembly, confirm the full assembly — including frame, door, and all hardware — meets the applicable fire door listing requirements per local building code. Adjust closing speed and tension using the manufacturer-provided adjustment mechanism after the hinge is fully fastened and the door is hung.