PDQ 35-STHB-4545-NRP, 5 Knuckle 4 Ball Bearing, Heavy Weight , Steel, Full Mortise Hinge, - 4 1/2" x 4 1/2"

The PDQ 35-STHB-4545-NRP is a heavy-weight, 5-knuckle, 4-ball-bearing full mortise hinge in steel, sized 4-1/2 by 4-1/2 inches, with a non-removable pin. It's built for high-frequency commercial openings where a standard hinge would wear out, the heavy doors and high-traffic doors that swing thousands of times a week. The model code tells you what you're getting: ST is steel, HB is the heavy-weight ball bearing grade, 4545 is the size, and NRP is the non-removable pin. Among PDQ hinges, the heavy-weight ball bearing line is the one specified when durability and door weight are the priority.

What the STHB heavy-weight ball bearing design gives you

The four ball bearings are the heart of it. Two bearings handle a standard-weight hinge, but the heavy-weight STHB uses four, spreading the load so the hinge carries heavier doors and survives far more cycles before it shows wear. PDQ cycle-tests its heavy-weight ball bearing hinges to the Grade 1 standard, which is built for the highest-frequency commercial use. For entrance doors, fire-rated openings, and any door that takes constant traffic, that bearing count is the difference between a hinge you replace and one you forget about.

The full mortise design means both leaves mortise into the door and the frame, the standard commercial mounting, and the hinge is swaged to give 1/16 inch of clearance between the leaves when closed.

Why the non-removable pin (NRP) matters

The NRP is a security feature, and it matters on a specific type of opening. On an out-swing door, the hinge barrel and pin sit on the exterior side, which means an intruder could in theory tap the pin out and lift the door off its hinges. The non-removable pin stops that: a groove in the pin accepts a set screw in the center barrel, and that set screw is tightened with a 3/32 inch hex wrench and sits where it can't be reached when the door is closed. So for any out-swinging exterior or secured door, the NRP version is the right call. On interior in-swing doors where the pin isn't exposed, NRP is optional but does no harm.

PDQ 35-STHB-4545-NRP specifications

• Type: Full mortise hinge, 5 knuckle, 4 ball bearing, heavy weight.

• Size: 4-1/2 by 4-1/2 inches. Thickness 0.180 inch.

• Material: Steel, for interior doors and non-corrosive environments.

• Pin: Non-removable pin (NRP), set screw secured, not accessible when the door is closed.

• Swaging: Standard, 1/16 inch clearance between leaves when closed.

• Frequency: High-frequency use.

• Bearings: Four ball bearings for heavy-door, high-cycle service.

• Fasteners: Ships with machine screws (12-24 x 1/2 inch FHMS) and wood screws (12 x 1-1/4 inch FHWS).

• Compliance: Conforms with NFPA 80 for fire door assemblies. Verify the exact ANSI/BHMA A156.1 grade and UL listing for this SKU against PDQ's current cut sheet.

• Warranty: PDQ limited warranty.

Why specify PDQ hinges

PDQ builds commercial door hardware in the US with a focus on Grade 1 and Grade 2 performance at a sensible price, and the hinge line follows the same logic. The heavy-weight ball bearing series gives you the durability of a top-tier hinge without the premium of the biggest-name brands, which is why contractors and facility managers spec PDQ hinges across multifamily, institutional, and commercial projects. Matching hinge weight to door weight is the decision that matters most: a heavy or high-traffic door needs the heavy-weight 4-bearing hinge, while a light interior door can use a standard 2-bearing version, so size the hinge to the door rather than defaulting to one for the whole building.

Order the PDQ 35-STHB-4545-NRP from American Locksets

We stock the full PDQ hinge line from authorized distribution, so every hinge ships with a valid manufacturer warranty. Compare sizes, weights, and finishes in the PDQ hinges category, or browse all door hinges.