SOSS 418 Series Invisible Hing...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$308.28
$238.00
SOSS 418 Series Invisible Hinge, 4-5/8" Full Mortise Door Hinge for 1-3/4" Minimum Thickness Doors

SOSS 418 Series Invisible Hinge, 4-5/8" Full Mortise Door Hinge for 1-3/4" Minimum Thickness Doors

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Model: 418US26D
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In Stock (leaves warehouse same day if ordered before 3pm ET)

$308.28
$238.00
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SOSS 418 Series Invisible Hinge, 4-5/8" Full Mortise Door Hinge for 1-3/4" Minimum Thickness Doors

The SOSS 418 Series Invisible Hinge is a full-size, 4-5/8" door style hinge engineered for wood or metal door applications with a minimum material thickness of 1-3/4". Constructed of alloy steel, this hinge delivers a flush, concealed fit with compact size and smooth single-action operation, opening a full 180°. The model #418 carries an Underwriters Laboratories fire rating up to and including 3 hours (180 minutes) on hollow metal, sheet metal, tin clad, and steel composite swinging fire doors and frames, plus additional ratings for wood core and wood/plastic composite door and frame constructions.

Key Features

  • Full Size Application: Designed for wood or metal doors with 1-3/4" minimum material thickness for reliable full-size entry door installations.
  • Compact 4-5/8" Profile: Product size of 4-5/8" delivers a flush, invisible fit with compact dimensions and smooth operation.
  • Heavy-Duty Alloy Steel Construction: Built from alloy steel to provide superior appearance and durability in demanding commercial applications.
  • 180° Single-Action Operation: Opens a full 180° as a single action hinge for versatile door swing requirements.
  • Fire Rated Performance: UL labeled for use on hollow metal, sheet metal, tin clad, and steel composite fire doors and frames rated up to and including 3 hours; wood core doors and frames up to 20 minutes; and wood/plastic composite doors and frames constructed with Georgia Pacific FS 1 or FS 2 banding rated up to and including 90 minutes.
  • Hardware Included: Wood and machine screws are included for straightforward installation.
  • Fire Door Hinge Spacing 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 and including 3 hours on hollow metal, sheet metal, tin clad, and steel composite doors/frames
  • Fire Rated up to 20 minutes on wood core doors and frames
  • Fire Rated up to and including 90 minutes on wood/plastic composite doors and frames (Georgia Pacific FS 1 or FS 2 banding)

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: Radius
  • Series: 418 Series
  • Product Size: 4-5/8"
  • Product Category: Door Hinges and Pivots
  • Department: Door Hardware
  • Application: Full Sized Entry, Metal, Wood
  • Min. Material Thickness: 1-3/4″
  • Fire Rating: 90 / 180 Minutes
  • Power Transfer: No
  • Closer: No
  • Counter Bored Screw Holes: No
  • Screws Included: Wood and 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 418?

SOSS 418 Series hinges combine alloy steel construction with a fire-rated design tested for use up to 3 hours on metal doors and frames, delivering the flush, invisible appearance and smooth 180° single-action operation that full-size entry doors demand. Engineered for commercial-grade wood and metal door applications where durability, compact fit, and code-compliant fire performance are essential.

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:
Radius
Series:
418 Series
Product Function:
Invisible Hinges
Product Size:
4-5/8"
Product Category:
Door Hinges and Pivots
Product Substrate:
Alloy Steel
Department:
Door Hardware

SOSS 418US26D – Frequently Asked Questions

1) Will a SOSS 418 invisible hinge work on a 1-3/8 inch door?
No. The 418 needs 1-3/4 inch minimum material thickness, so a 1-3/8 inch leaf (the common older interior thickness) is too thin to take it. It is built for full size entry work on 1-3/4 inch and heavier wood or metal doors. If your leaves are 1-3/8 inch, you need a hinge rated for that thickness instead.
2) Can I use a SOSS 418 concealed hinge on a fire rated opening?
Yes, and the rating you get depends on what the door and frame are made of. The model 418 is UL labeled to 3 hours (180 minutes) on hollow metal, sheet metal, tin clad and steel composite doors and frames. On wood core doors and frames it is good to 20 minutes. On wood and plastic composite doors and frames built with Georgia Pacific FS 1 or FS 2 banding it goes up to 90 minutes. So a 90 minute wood opening only holds its label if the door carries that banding; a plain wood core assembly caps at 20 minutes.
3) Does an invisible hinge like the SOSS 418 let the door swing all the way back to the wall?
Full 180 degrees, as a single action hinge, so the leaf can come all the way back against the adjacent surface rather than stopping short. Single action means it swings one way from closed, not both. If you need the door to push through in both directions, this is the wrong hinge type.
4) Why use a concealed invisible hinge instead of a standard butt hinge on a commercial door?
A butt hinge sits on the face of the door edge and jamb with the barrel and pin showing when the door is shut. The SOSS 418 is a full mortise invisible hinge: it buries in pockets cut into the door edge and the jamb, so nothing shows on either face with the door closed. That is the reason to pick it, along with alloy steel construction at a heavy duty level for commercial traffic. The trade off is prep. A butt hinge screws to a shallow mortise or straight to the surface, while the concealed hinge needs a routed pocket in both the door and the frame. If you cannot rout accurately on site, a butt hinge is the practical call.
5) Is there an exposed hinge pin on a SOSS 418 that someone could attack on an outswing door?
No knuckle and no pin are visible with the door closed. The 418 mortises fully into the door edge and the jamb, so the whole hinge is inside the opening. On an outswing door a conventional butt hinge puts its pin on the exterior side, which is why non removable pins or security studs get specified there. An invisible hinge removes that exposure entirely.
6) Can a SOSS 418 invisible hinge carry power through the door for an electric strike or electrified lock?
No. The 418 is a mechanical hinge with no electronics and no power transfer, so it will not run wire from the frame to the door. An access controlled opening using these hinges needs a separate transfer device, either an electric power transfer hinge or a concealed door loop, in addition to the 418s carrying the leaf.
7) What size mortise does the SOSS 418 need, and are the pocket corners square or rounded?
The hinge body is the 4-5/8 inch size, and the corner type is radius. A radiused end is what a router bit naturally produces, so the pocket does not have to be chiselled square at the corners the way a square cornered leaf demands. Cut the pockets in the door edge and in the jamb to match the hinge, and keep in mind the 1-3/4 inch minimum material thickness the routing has to live inside.
8) What finishes does the SOSS 418 invisible hinge come in, and will it match my other door hardware?
Five finishes: 619 satin nickel, 626 satin chrome, 606 satin brass, 622 matte black, and UNP unplated. Those are standard BHMA finish numbers, so 626 on the 418 is specified against the same number as the 626 lockset or closer on the same opening. Worth remembering that the hinge is concealed once the door is shut, so finish here is about the exposed knuckle when the door stands open rather than about what shows on the closed face.
9) Do SOSS 418 hinges come with screws, or do I have to supply fasteners?
Both wood and machine screws are in the box, so the same hinge covers a wood door and jamb or a metal one without a separate fastener order. The screw holes are not counter bored, which is worth knowing if your detail expects a flush seated head.
10) Will a SOSS 418 hinge close the door on its own, or do I still need a door closer?
You still need a closer. There is no closing or spring function built into the 418, it only hangs and swings the leaf. On a fire rated opening that matters, because the assembly has to self close and latch, so budget a separate closer alongside the hinges.
11) Are SOSS 418 hinges heavy duty enough for a solid core entry door in a commercial building?
Yes. Alloy steel body, rated heavy duty, and specified for commercial rather than residential service, which is the class of hinge that belongs on a full size entry leaf in offices, schools, healthcare, retail and multi tenant buildings. The practical sizing check is weight: figure one hinge per 60 lbs of door or fraction of it, and add hinges until the count also satisfies one per 20 inches of door height.
How fast can I get the SOSS 418US26D 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 418US26D come with a warranty?
Absolutely. The SOSS 418US26D 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 418US26D?
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 418US26D from ZenSupply?
ZenSupply makes it easy to get the commercial door hardware you need—fast shipping, expert support, and rewards on every order. Our team is always ready to help you choose the right product for your project.
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