SOSS 420 Series Invisible Hing...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$341.96
$265.00
SOSS 420 Series Invisible Hinge with 3-Hour Fire Rating for 2" Minimum Metal Doors

SOSS 420 Series Invisible Hinge with 3-Hour Fire Rating for 2" Minimum Metal Doors

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Model: 420US26D
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In Stock (leaves warehouse same day if ordered before 3pm ET)

$341.96
$265.00
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SOSS 420 Series Invisible Hinge with 3-Hour Fire Rating for 2" Minimum Metal Doors

The SOSS 420 Series Invisible Hinge is a full size, 4-1/2" x 4-1/2" single action hinge engineered for metal applications with a minimum material thickness of 2". Constructed of alloy steel, the model #420 opens a full 180° and is Underwriters Laboratories labeled for use on hollow metal, sheet metal, tin clad, and steel composite swinging type fire doors and frames rated up to and including 3 hours (180 minutes), as well as wood core doors and frames rated up to 20 minutes. Designed for full sized entry applications in both metal and wood door construction, this heavy duty hinge delivers a flush fit, compact profile, and smooth operation for demanding commercial installations.

Key Features

  • Full Size Profile: 4-1/2" x 4-1/2" product size suited for full sized entry door applications.
  • Minimum Material Thickness: Designed for metal applications that are 2" thick, ensuring proper fit and function.
  • Fire Rating: UL labeled for use on hollow metal, sheet metal, tin clad, and steel composite swinging type fire doors and frames rated up to and including 3 hours (180 minutes), and wood core doors and frames rated up to 20 minutes.
  • Heavy Duty Alloy Steel Construction: Built from alloy steel for superior appearance and long-term durability in commercial environments.
  • Full 180° Single Action Operation: Opens a full 180° for smooth, reliable single action swinging performance.
  • Invisible Flush Fit Design: Compact, concealed hinge design provides a clean flush appearance where visible hardware is undesirable.
  • Machine Screws Included: Ships complete with machine screws for straightforward installation.
  • Fire-Rated Hinge Application Guidance: Use at least one fire-rated hinge for every 20" of door height or portion thereof, or one hinge for every 60 lbs. or fraction thereof, whichever calculation demands more hinges.

Certifications & Compliance

  • Underwriters Laboratories (UL) Labeled
  • Fire Rated up to 3 Hours (180 Minutes) on Metal Doors and Frames
  • Fire Rated up to 20 Minutes on Wood Core Doors and Frames

Technical Specifications

  • Subcategory: Hinges and Pivots
  • Commercial/Residential: Commercial
  • Product Group: Door Hinges and Pivots
  • Product Type: Hinges and Pivots
  • Duty Level: Heavy Duty
  • Electronic: No
  • Corner Type: Square
  • Series: 420 Series
  • Product Size: 4-1/2" x 4-1/2"
  • Product Category: Door Hinges and Pivots
  • Department: Door Hardware
  • Application: Full Sized Entry, Metal, Wood
  • Min. Material Thickness: 2″
  • Fire Rating: 180 Minutes
  • Power Transfer: No
  • Closer: No
  • Counter Bored Screw Holes: No
  • Screws Included: Machine
  • Packaging: 1 / Box = 1 Each
  • Packages Per Container: 1 Each
  • Price Per: Each

Typical Applications

  • Commercial Office Buildings
  • Educational Facilities
  • Healthcare Institutions
  • Retail Establishments
  • Industrial and Warehouse Facilities
  • Multi-Tenant Residential Properties
  • Government and Municipal Buildings

Why SOSS 420?

SOSS 420 Series invisible hinges deliver professional-grade reliability with heavy duty alloy steel construction and a UL label supporting fire ratings up to 3 hours on metal doors and frames. Engineered for demanding commercial applications where a flush fit, compact size, and smooth 180° single action operation are essential, this hinge is a dependable choice for full sized entry doors in both metal and wood construction.

Product Specs

Subcategory:
Hinges and Pivots
Commercial/Residential:
Commercial
Product Group:
Door Hinges and Pivots
Product Type:
Hinges and Pivots
Product Subgroup:
Invisible Hinges
Duty Level:
Heavy Duty
Electronic:
No
Corner Type:
Square
Series:
420 Series
Product Function:
Invisible Hinges
Product Size:
4-1/2"
Product Category:
Door Hinges and Pivots
Product Substrate:
Alloy Steel
Department:
Door Hardware

SOSS 420US26D – Frequently Asked Questions

1) Can I use the SOSS 420 invisible hinge on a 3-hour rated hollow metal door?
Yes. The SOSS model 420 carries a UL label for hollow metal, sheet metal, tin clad, and steel composite swinging fire doors and frames rated up to and including 3 hours (180 minutes). On wood core doors and frames the label covers up to 20 minutes, so a 45 or 90 minute wood opening is outside what this hinge is labeled for.
2) What is the minimum material thickness for the SOSS 420 invisible hinge?
Two inches. The 420 is cut for metal applications with a minimum material thickness of 2 inches, which is thicker than a standard 1-3/4 inch commercial door. If your leaf and jamb are 1-3/4 inch stock, this is the wrong model in the SOSS invisible line and you want a hinge sized for that thickness instead.
3) Does an invisible hinge like the SOSS 420 open far enough for a full swing entry door?
It opens a full 180 degrees, single action, so the leaf lays back flat against the wall the way a butt hinge would. Single action means it swings one direction only, not both, so it is not a substitute for a double acting pivot on a traffic door.
4) Why choose an invisible hinge instead of a standard butt hinge on a commercial entry?
An invisible hinge mortises entirely into the edge of the leaf and the jamb, so nothing shows with the door closed, no knuckle, no leaves, no exposed pins. That is the reason to spec the 420: openings where visible hardware is unwanted and a flush edge matters, like architectural office fronts or clean healthcare corridors. A butt hinge is cheaper and simpler to prep. The 420 is heavy duty alloy steel, so it is doing the concealment without giving up load capacity.
5) What size is the SOSS 420 and does it come with screws?
The 420 is a full size 4-1/2 inch by 4-1/2 inch hinge with square corners, and it ships with machine screws. Machine screws, not wood screws, which is consistent with the metal door application it is cut for. Packed one per box, sold each.
6) Do I have to specify handing when ordering a SOSS 420 invisible hinge?
No handing to call out on the 420. The hinge is non-handed and the swing direction is set by which edge of the door and jamb you mortise it into. What you do need to settle before ordering is quantity per leaf from the 20 inch height and 60 lb weight rule, and the finish.
7) Is the SOSS 420 electrified or can it carry power to the door?
No. The 420 is a purely mechanical hinge with no power transfer and no closer built in. If the opening needs an electric strike, mag lock, or a card reader on the door leaf, you will need a separate electric power transfer or a door loop, and a closer specified on its own.
8) Where do I find the mortise prep and clearance dimensions for the SOSS 420?
SOSS publishes the prep drawings for the 420 as separate details: a model drawing for the hinge itself, a hinge location detail for spacing up the leaf, a cased jamb detail, a 90 degree open view, and an open clearance detail. Pull the clearance and jamb details before you cut, since an invisible hinge is routed into both the door edge and the frame and there is no adjusting it after the mortise is made.
9) What finishes does the SOSS 420 invisible hinge come in?
Four: unplated (UNP), 622 matte black, 626 satin chrome, and 606 satin brass. Since the hinge is concealed when the door is closed, finish only shows on the exposed knuckle area when the leaf is open, so most buyers standardizing a building match it to the lockset or simply run unplated where nothing is seen.
10) Is the SOSS 420 invisible hinge rated for high traffic commercial openings?
It is built for them. Alloy steel, heavy duty, and classified for commercial rather than residential use, which is what a property manager or facilities buyer wants behind a full sized entry door in an office building, school, hospital, retail space, or municipal building. The concealment does not come at the cost of the duty level.
How fast can I get the SOSS 420US26D delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the SOSS 420US26D come with a warranty?
Absolutely. The SOSS 420US26D is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the SOSS 420US26D?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the SOSS 420US26D from ZenSupply?
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