Schlage Commercial 40-104 Pin Tumbler Key Gauge

The 40-104 is a key gage for reading the depth of cuts on an already-cut Schlage key. You lay the key in the gage and it tells you the depth number at each cut position, which gives you the bitting so you can pick the right pin stack when rekeying a Schlage cylinder. It decodes an existing key; it does not cut keys and it does not include pins.

Keyway doesn't matter. The 40-104 works with any Schlage key across all Schlage keyways, because it reads cut depth at the blade rather than keying off the milling. The one exclusion is SFIC, small format interchangeable core keys are not covered.

No. The 40-104 gage is cut to Schlage's depth increments only, so readings off another manufacturer's key will be wrong. For non-Schlage cylinders you need a decoder or depth-and-space card made for that brand's system.

No, SFIC is specifically excluded from the 40-104's coverage. If you're maintaining an SFIC system you'll need a decoding tool built for that format. The 40-104 covers standard and full-size Schlage cylinder keys.

They do different jobs and most people running a Schlage system carry both. The 40-104 gage only reads depths off an existing key so you know what bitting you're working from. It carries no pins, so the actual rekey still needs a Schlage pin kit and a follower. Where the gage earns its place is when you have a key in hand and no bitting record for it, which is the normal situation on a building you just took over.

It's part of Schlage's commercial line, sold as a door hardware installation accessory. That matters mostly for who it's aimed at, a locksmith or in-house maintenance shop servicing Schlage cylinders across a facility, rather than a one-lock homeowner job.

One version only, model 40104. There are no finish, size, or keyway options to specify because the gage covers every Schlage keyway.