About this item
The BEST 8K37AB 4D S3 626 is a heavy-duty commercial cylindrical entrance knob lock from the BEST 8K Series Grade 1 platform, the institutional-spec line built for high-traffic openings in offices, schools, multi-family buildings, hospitals, and government facilities. The full part number breaks down as: 8K (Grade 1 cylindrical knob lock series), 3 (cylinder type), 7 (function digit for entrance/office), AB (knob style code), 4D (D rose convex round), S3 (4-7/8" curved-lip ANSI strike with box), 626 (satin chrome finish). Buyers will see this product co-branded as Stanley/BEST on legacy spec sheets because BEST was a Stanley Black and Decker brand before dormakaba acquired it in 2018. The mechanical product is unchanged. ANSI/BHMA A156.2 Series 4000 Grade 1 certified, UL Listed for 3-hour A-label single or double swinging fire doors, California State Fire Marshal listed. SKU 8K37AB4DS3626. In stock.
Is This the Right Stanley Door Knob for You?
Search results for "Stanley door knob" return a mix of residential big-box hardware and commercial-grade Stanley/BEST locks. They are not the same product. This 8K37AB is a Grade 1 commercial entrance knob lock priced and built for institutional duty cycles measured in millions of operations. If the door is in a single-family home and the budget is residential, this is not the lock; look at residential Stanley or Defiant lines instead. If the door is in an office building, school corridor, apartment unit, hospital corridor, or any commercial opening that takes daily abuse, the 8K37AB is exactly what spec writers reach for. The "AB" knob style is the angled smooth knob design. The "4D" rose is a convex round rose 3-3/8" in diameter that mounts cleanly on standard 2-1/8" cross-bore prep.
Function: ANSI F109 Entrance Lock Explained
The 8K37AB carries ANSI function F109 (also labeled F81 x F82 in older catalogs). The latch retracts by rotating either knob, by turning the outside key, or by closing the door if the inside push button is not engaged. The outside knob locks when the inside push button is pushed in. If the inside button is pushed and turned, the outside knob stays locked even after each use until the button is turned back. The inside knob is always free for unobstructed egress, which is what makes this an ANSI Grade 1 code-compliant entrance function. Use F109 on offices, apartment unit doors, secondary entries, dorm rooms, and any opening that needs keyed entry from outside with always-free egress from inside.
Specifications
Function: ANSI F109 entrance lock with deadlocking latchbolt. Chassis: 2-1/16" diameter, fits standard 2-1/8" cross-bore. Backset: 2-3/4" standard; 3-3/4" and 5" available. Latchbolt: 9/16" throw, deadlocking, 2-1/4" x 1-1/8" beveled front, fits 1" edge bore. Knob: machined from solid brass or bronze, 2-7/8" projection from door face. Rose: 4D convex round, 3-3/8" diameter, brass or bronze with steel reinforcement liner, threaded chassis attachment. Strike: S3 ANSI strike 4-7/8" x 1-1/4" with curved lip and box (ANSI A115.2). Door thickness: adjustable 1-3/8" to 2" standard. Internal parts: brass or corrosion-treated steel. Cylinder: accepts BEST 6-pin or 7-pin Small Format Interchangeable Core (SFIC). Compliance: ANSI/BHMA A156.2 Series 4000 Grade 1, UL Listed for 3-hour A-label fire doors single or double swing, California State Fire Marshal Listed.
Core Options
Two purchase options in order: Accepts BEST IC Interchangeable Core (core not included), or With BEST-Compatible Core and Keys Included (Arrow and similar SFIC compatible). Most facility spec writers managing existing BEST keyway inventory order the lock without core and pin to the existing system. New installations or single-door replacements typically order with the core and keys included.
Where This Fits in the BEST Catalog
The 8K series is the Grade 1 cylindrical knob platform, sitting above the BEST 6K Series Grade 2 (medium-duty commercial) and below the BEST 45H Series mortise platform.
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