By Kent · Lock Depot Staff Writer

A rim cylinder that takes a full-size core

A night latch, a rim exit device or a Schlage rim lock all want a cylinder that screws in from the back of the door and drives the lock with a tailpiece. The Schlage 20-057 is that cylinder, built for the full-size interchangeable core system. The part number is long, and every piece of it means something when you place the order. This guide reads the number the way the catalog presents it, so you do not end up with a C keyway on a door that needed a C123, or a bright brass cylinder on a satin chrome door.

What the listing tells us about the cylinder

Take the 20-057-C-626 as the starting point. The listing gives these facts:

• Type: FSIC rim cylinder.
• Pins: 6-pin.
• Keying: 1 bitted, with 2 keys.
• Cam type: convertible tailpiece.
• Handing: non-handed.

Non-handed means you do not order a left or a right. One part number covers either swing. The convertible tailpiece is the part that matters in the field. A rim cylinder lives or dies on how its tailpiece meets the lock behind it, and a convertible one is made to be set up for the lock you are mounting it on. The listing does not say which locks the tailpiece converts to, so check your lock's instructions before you assume it fits. We do not publish a compatibility list we do not have.

Reading the number: 20-057-C-626

Break it into three parts.

• 20-057 is the cylinder: the FSIC rim cylinder.
• C is the keyway.
• 626 is the finish.

That is the whole code. Nothing else in the part number changes the cylinder, so once you know the keyway and the finish you know the part.

Keyway: C, C123 and the rest

This is the choice that matters most, because the keyway has to match the rest of the building. The catalog carries the 20-057 in more than two dozen keyway codes. The C family is the bulk of it: C, C123, C124, C125, C145, C134, C234, C235, C245, C345 and CE. The list also includes E, EF, F, FG, G, P, ICC and the S-prefixed codes such as S123 and S345. The ones we checked come in all nine finishes.

Schlage describes its key systems as layered security. You can run a standard open keyway on some doors and a restricted one on others, all under one keyway design. The listing says exactly that, and it is why the codes read as a family: they all begin with C. We are not going to guess what each added digit stands for, because the listing does not say and the wrong guess puts a cylinder on the shelf that no key will turn.

The working rule is simple. Match the keyway to the cores already in the building. Pull a core from a door nearby, read the keyway stamped on it or ask whoever owns the key system, and order that exact code. A plain C and a C123 are different keyways. They are not interchangeable.

The cylinder to start with for a plain system is the C keyway in satin chrome. If your system uses the C123 keyway, the 20-057-C123-626 is the same cylinder and the same finish with the other keyway.

The nine finishes

Each keyway is stocked in the same nine finishes. The names come straight from the listings:

• 605: bright brass, see 20-057-C-605.
• 606: satin brass.
• 609: antique brass.
• 612: satin bronze, see 20-057-C-612.
• 613: oil rubbed bronze.
• 619: satin nickel, see 20-057-C-619.
• 622: black coated.
• 625: bright chrome, see 20-057-C-625.
• 626: satin chrome.

The cylinder is a small part, but it is the one people see. A bright brass cylinder on a satin chrome lock looks like a mistake and tells the next person someone swapped parts. Look at the lock trim in front of you and match its finish. When two finishes look close under shop lights, they will not look close on a sunny wall, so check against the lock itself, not memory.

Where this cylinder fits in a core system

A full-size interchangeable core system exists so a building can be rekeyed without taking locks apart. You pull the old core with a control key and put in a new one. The rim cylinder is one housing in that system. A building with FSIC hardware on its mortise doors, its cylindrical doors and its night latches can run them all on one key plan, and the rim cylinder is how the night latch and the rim exit device join that plan. For the mortise side, the Schlage 26-091 and 20-091 are the mortise cylinders in the same family.

If your building runs a different core size, a different brand's system does the same job at a different format. Our guide to small format cores and control keys explains the idea in that size. Do not mix the two. A small format core will not seat in a full-size housing.

Ordering a batch

If you are doing a whole building, make a table before you call: door number, lock model, keyway, finish, quantity. Fill the keyway column once from the building's key plan, the same way you would for matching a rim cylinder keyway on a night latch. It should be the same for every door that shares a system. Then the order reads as full part numbers, and nobody on the phone has to ask you what you meant. Every keyway we checked is stocked in all nine finishes, so the finish you want is rarely the problem. The keyway is.

The full Schlage line is on our Schlage page. If you are matching an existing cylinder, bring the keyway off a core and the finish off the trim, and we will find the part.

Common mistakes

The first is ordering the cylinder without the keyway. 20-057 alone is not a part number. The second is assuming C and C123 are the same. They are different keyways. The third is assuming the tailpiece fits your lock because the listing says convertible. Check the lock first. The fourth is buying the finish from memory and finding out it was satin nickel after the box arrives.

Common questions

What is the Schlage 20-057?

It is a Schlage FSIC rim cylinder, 6-pin, 1 bitted, supplied with 2 keys, with a convertible tailpiece and no handing.

How many keyways does the 20-057 come in?

More than two dozen. The C family, C123 through C345 and CE, makes up most of them, along with E, F, G, P, ICC and the S-prefixed codes.

What finishes does it come in?

Nine: bright brass, satin brass, antique brass, satin bronze, oil rubbed bronze, satin nickel, black coated, bright chrome and satin chrome.

Do I need to choose a left or right hand?

No. The listing says non-handed.

Is it a mortise cylinder?

No. It is a rim cylinder. The mortise versions are the 26-091 and 20-091.