{"product_id":"national-marker-n185-199-spring-door-hinge-3-5-in","title":"National Marker N185-199 Spring Door Hinge 3.5 in","description":"\u003ch3\u003eProduct Description\u003c\/h3\u003e\n\u003cp\u003eThe NATIONAL MARKER N185-199 is a self-closing spring door hinge designed for hanging doors that must automatically return to a closed position after each use. Built from cold-rolled steel with a 3.5-inch leaf size and a 0.25-inch radius corner profile, this hinge fits standard hinge cutouts without modification. It carries UL approval for fire door applications, making it a code-relevant choice wherever rated door assemblies are required. Closing speed is field-adjustable, allowing installers to tune door swing to suit traffic volume and occupant needs. Sold as a single unit.\u003c\/p\u003e\n\u003cp\u003eThis hinge is suited for residential, commercial, and multi-unit apartment installations. Common install locations include basement access doors, interior stairway doors, garage entry doors, and building entrance doors where self-closing function is required by fire code or building management policy. The adjustable spring mechanism makes it practical across a range of door weights and use frequencies. It is cataloged under the V521 series.\u003c\/p\u003e\n\u003ch4\u003eKey Features\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003eUL approved for fire door applications, supporting code-compliant installations\u003c\/li\u003e\n  \u003cli\u003eAdjustable closing speed to accommodate different door weights and traffic levels\u003c\/li\u003e\n  \u003cli\u003eCold-rolled steel construction for durability in high-cycle door applications\u003c\/li\u003e\n  \u003cli\u003e0.25-inch radius corner profile fits standard hinge cutouts without additional mortising\u003c\/li\u003e\n  \u003cli\u003eSuitable for residential, commercial, and apartment building use\u003c\/li\u003e\n  \u003cli\u003eSelf-closing spring mechanism eliminates the need for a separate door closer on light-duty applications\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eCompatibility\u003c\/h4\u003e\n\u003cp\u003eDesigned as an OEM-style replacement or new-installation spring hinge for standard residential and commercial interior doors requiring self-closing function, including UL-listed fire door assemblies.\u003c\/p\u003e\n\u003ch4\u003eInstallation Notes\u003c\/h4\u003e\n\u003cp\u003eInstallation is typically performed by a carpenter, general contractor, or facilities maintenance technician. Shut the door and secure the work area before removing any existing hardware. The adjustable spring tension should be set after the hinge is fully mortised and fastened, following the door manufacturer's torque guidance for hinge screws. Fire door installations must conform to the applicable building and fire codes in the jurisdiction, including NFPA 80 requirements for labeled door assemblies.\u003c\/p\u003e\n\u003ch4\u003eTechnical Specifications\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLeaf Size\u003c\/strong\u003e: 3.5 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCorner Radius\u003c\/strong\u003e: 0.25 inches\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\u003eListing\u003c\/strong\u003e: UL approved for fire doors\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWeight\u003c\/strong\u003e: 0.765 pounds\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSeries\u003c\/strong\u003e: V521\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: N185-199\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"NATIONAL MARKER","offers":[{"title":"Default Title","offer_id":51345440604466,"sku":"N185-199","price":30.68,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0270\/4519\/9983\/files\/310550245.jpg?v=1782058294","url":"https:\/\/voomisupply.com\/products\/national-marker-n185-199-spring-door-hinge-3-5-in","provider":"Voomi Supply","version":"1.0","type":"link"}