McKinney SQ3331 4-1/2 x 4-1/2 Standard Weight Square Barrel Full Mortise Hinge
The McKinney SQ3331 is a 4-1/2 inch x 4-1/2 inch full mortise, standard weight butt hinge featuring a distinctive square barrel (square knuckle) design. Unlike conventional round-knuckle hinges, the SQ3331 delivers a crisp, angular silhouette that complements contemporary and institutional architectural millwork. As a full mortise hinge, both leaves seat flush into routed mortises on the door edge and frame, producing a clean, professional installation with no surface-mounted hardware visible when the door is closed. The SQ3331 is part of McKinney's square-barrel hinge program — a go-to specification for architects and hardware consultants who require a squared architectural appearance on commercial and institutional door openings.
Institutional Grade Features & Benefits
- Square Barrel Knuckle: The hallmark of the SQ3331 is its squared knuckle barrel profile, providing a refined, geometric aesthetic that pairs naturally with modern hollow metal frames, wood doors, and contemporary aluminum storefronts.
- Full Mortise Installation: Both hinge leaves are fully recessed (mortised) into the door edge and door frame, ensuring a flush, tamper-resistant fit and a clean architectural finish.
- Standard Weight Construction: At 0.134 in. steel leaf thickness, the SQ3331 delivers dependable performance suitable for standard commercial door applications without the added bulk of heavy-weight hinges.
- 4-1/2 x 4-1/2 Inch Leaf Dimensions: This generous leaf size provides broad bearing surface and stable swing support, appropriate for standard-height commercial doors.
- McKinney Quality: McKinney is a long-established, widely specified commercial door hardware brand trusted by architects, general contractors, and institutional facility managers across North America.
Technical Details
| Feature | Details |
|---|---|
| Brand | McKinney |
| Part Number | SQ3331 |
| Part Type | Hinge — Full Mortise Butt Hinge |
| Hinge Size | 4-1/2 in. x 4-1/2 in. |
| Barrel / Knuckle Style | Square Barrel (Squared Architectural Appearance) |
| Weight Class | Standard Weight |
| Gauge / Leaf Thickness | 0.134 in. steel leaf thickness |
| Mounting Type | Full Mortise |
Documentation
| General - US Finishes | US26D - Satin Chrome or US15 - Satin Nickel or US10B - Oil Rubbed Bronze |
| Door Handing | LH or RH |
| Brand | McKinney |
| Hinge Type | Square Barrel |
| Hinge Mounting | Full Mortise |
| Hinge Height | 4.5" Hi |
| Hinge Width | 4.5" Wi |
| Hinge Grade/Thickness | Standard Wt .119 to .146 |
| Hinge Corners | Square |
| Base Material | Steel |
| Part Type | Hinge, Hinge |
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