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

The PDQ 35-STBB-4545-NRP is a full mortise hinge from PDQ's 35 Series commercial hinge line. If you searched "pdq 35" or "pdq35"-the 35 is PDQ's designation for their full mortise hinge platform. Every position in the model code tells you exactly what you're getting, and understanding that code is what separates a correct order from a return.

Decoding the 35-STBB-4545-NRP Model Code

35 = PDQ's 35 Series full mortise hinge. This is the series identifier-not a size, not a weight, not a finish.

ST = steel base material. PDQ's 35 Series ships in two base materials: ST (steel) and SS (stainless steel). The ST versions are steel with standard commercial finishes applied. The SS versions are stainless steel, which is the correct specification for exterior doors, coastal environments, and applications where finish durability over decades is a requirement. Never substitute ST for SS on exterior hardware without confirming finish suitability.

BB = ball bearing configuration: 2 ball bearings. PDQ uses BB for 2-bearing and HB for 4-bearing. The 2-bearing configuration is standard weight, for medium-frequency-of-use doors. The 4-bearing (HB) configuration handles heavy weight doors and high-frequency applications like school corridors and hospital doors that open and close hundreds of times a day. For standard commercial interior doors in offices, retail, and residential buildings, 2-bearing (BB) is the correct specification.

4545 = hinge size: 4-1/2 inches by 4-1/2 inches. The first two digits are height, the second two are width. A 4-1/2 x 4-1/2 square hinge is the standard commercial size for 1-3/4-inch doors up to 200 pounds. If your door is wider or heavier, specify the 5-inch x 4-1/2-inch (5045) variant.

NRP = non-removable pin. When the door is closed, the pin cannot be extracted from the barrel even from the exterior side. On a hinge with a standard removable pin, an intruder with access to the hinge side of the door-such as a door that swings outward-could knock out the pin and lift the door off the frame without attacking the lock at all. NRP eliminates that vulnerability. This is a security specification, not a convenience feature, and it should be called out explicitly on any exterior or security-critical door.

Full Mortise vs Surface Hinge

Full mortise means both hinge leaves are mortised (recessed) into the door edge and door frame. Neither leaf is surface-applied. Full mortise hinges sit flush with the door and frame surfaces, providing a cleaner look and better load distribution than half-mortise or surface hinges. They're the standard specification for commercial hollow metal and wood doors in commercial construction.

Standard Weight vs Heavy Weight

The STBB is standard weight-the leaf thickness is .134 inches for the 4-1/2 x 4-1/2 size, certified to ANSI A8112. Standard weight is correct for doors up to approximately 200 pounds with medium frequency of use. For heavy doors, wide doors (over 36 inches), or high-traffic applications, specify the heavy weight 4-bearing version (STHB).

35 Series Variant Matrix

STBB = Steel, 2 ball bearing, standard weight

SSBB = Stainless steel, 2 ball bearing, standard weight

STHB = Steel, 4 ball bearing, heavy weight

SSHB = Stainless steel, 4 ball bearing, heavy weight

Specifications

Model: PDQ 35-STBB-4545-NRP

Series: PDQ 35 Series Full Mortise Hinge

Material: ST-Steel

Bearing: BB-2 ball bearings

Weight Class: Standard weight

Leaf Thickness: .134" ± .005"

Size: 4-1/2" x 4-1/2"

Pin: NRP-Non-removable pin

Knuckles: 5

Hinge Type: Full mortise

Frequency of Use: Medium

ANSI Certification: ANSI A8112

Sold: 3 hinges per carton

Finishes: 600 (primed), 605, 613E, 619, 622, 626, 652 and others

Heavy Weight Version: PDQ 35-STHB-4545-NRP

Stainless Version: PDQ 35-SSBB-4545-NRP-630

American Locksets has stocked PDQ 35 Series commercial hinges since launch.