Kwikset 85172-001 Cylinder for Knobs and Levers with Half Round Chassis and 917 and 955 Lever Electronics with SmartKey SC1 Keyway Black Finish

It's the replacement key cylinder that drops into Kwikset knobs and levers built on the half round chassis, including the 917 and 955 lever electronics. You're buying the cylinder itself, not the whole lockset, so it's the right part when the lock body is fine and you need to change or replace the keyed side. Black finish, SC1 keyway.

It's an SC1 keyway cylinder, so it accepts Schlage-style SC1 blanks, and it's SmartKey. SmartKey means you re-key it yourself in seconds with the learn tool and a working key, so if your building is already on one Kwikset SmartKey key, you can bring this cylinder onto that key instead of adding another one to the ring. If your other Kwikset locks are on the KW1 keyway, they won't cross-key with this one without re-keying the rest of the fleet.

Yes, keying is a required choice: keyed different (its own key) or keyed alike (matched to the other cylinders on the same order). There's also an optional key code field if you're matching an existing key code already in service in your building. Keying is free either way. Property managers replacing several cylinders across a floor should take keyed alike so maintenance carries one key.

It carries an ANSI/BHMA Grade 1 rating but is classified as residential hardware. That combination suits multi-family unit doors, apartments, and light-duty property management work where you want the highest cycle-rated residential product. For a true commercial opening on a spec drawing calling out Grade 1 commercial mortise or cylindrical hardware, spec a commercial-line cylinder instead.

Those are exactly the two lever electronics it's built for, along with Kwikset knobs and levers using the half round chassis. If your lock is a different Kwikset chassis type, or a deadbolt rather than a knob or lever, this isn't the matching cylinder.

Single cylinder. The 85172-001 is keyed on one side only, with a thumbturn or inside lever handling the interior, which is the normal arrangement for a knob or lever set. If you need key access from both sides, this isn't the part.

That's the point of SmartKey. A property manager or maintenance tech can re-key the cylinder on the door in under a minute with the existing working key and the SmartKey learn tool, no disassembly and no pinning kit. For a portfolio with tenant turnover, that's the difference between a service call per unit and a walk-through.

Black finish, SC1 keyway, and keyed alike as a free option, so a run of these will match visually and key to one key across a set of half round chassis Kwikset knobs and levers. Order them together on the same keyed alike selection so they come out on a common key.