{"product_id":"national-marker-n350850-spring-door-hinge-oil-rubbed-bronze","title":"National Marker N350850 Spring Door Hinge Oil Rubbed Bronze","description":"\u003ch3\u003eProduct Description\u003c\/h3\u003e\n\u003cp\u003eThe 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.\u003c\/p\u003e\n\u003cp\u003eThe 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.\u003c\/p\u003e\n\u003ch4\u003eKey Features\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003eSelf-closing spring mechanism with adjustable closing speed\u003c\/li\u003e\n  \u003cli\u003eUL approved for fire-rated door applications\u003c\/li\u003e\n  \u003cli\u003eCold-rolled steel construction for durability\u003c\/li\u003e\n  \u003cli\u003e1\/4-inch radius corners fit standard hinge cutouts\u003c\/li\u003e\n  \u003cli\u003eOil rubbed bronze finish for corrosion resistance and appearance\u003c\/li\u003e\n  \u003cli\u003eSuitable for residential, commercial, and multi-unit residential buildings\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eCompatibility\u003c\/h4\u003e\n\u003cp\u003eDesigned 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.\u003c\/p\u003e\n\u003ch4\u003eInstallation Notes\u003c\/h4\u003e\n\u003cp\u003eInstallation 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.\u003c\/p\u003e\n\u003ch4\u003eTechnical Specifications\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSeries\u003c\/strong\u003e: V521\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHinge Size\u003c\/strong\u003e: 4 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCorner Radius\u003c\/strong\u003e: 1\/4 inch\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFinish\u003c\/strong\u003e: Oil Rubbed Bronze\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMaterial\u003c\/strong\u003e: Cold-Rolled Steel\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eClosing Type\u003c\/strong\u003e: Adjustable Spring Self-Closing\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFire Rating\u003c\/strong\u003e: UL Approved for Fire Doors\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWeight\u003c\/strong\u003e: 0.891 pounds\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSold As\u003c\/strong\u003e: Each\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eStandard Information\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBrand\u003c\/strong\u003e: NATIONAL MARKER\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number\u003c\/strong\u003e: N350850\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"NATIONAL MARKER","offers":[{"title":"Default Title","offer_id":51343063777586,"sku":"N350850","price":30.17,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0270\/4519\/9983\/files\/310550647.jpg?v=1782015369","url":"https:\/\/voomisupply.com\/products\/national-marker-n350850-spring-door-hinge-oil-rubbed-bronze","provider":"Voomi Supply","version":"1.0","type":"link"}