What the Letters After a Model Number Mean

Open any Chinese hardware manufacturer's price list and you will find the same thing: four hundred lines that look like four hundred products, and are not. Somewhere in there are 607 PBBK, 607 ABET, 607 SNET and 607 BNET, and a buyer new to the catalog reasonably assumes these are four different locks that happen to share a number.

They are one lock. The digits are the product. The letters are the finish, and sometimes the function. Nobody writes this down, because inside a factory it is too obvious to explain and outside one there is no way to find out. So here it is written down.

The finish codes are two letters, and most of the set runs across the whole industry rather than being ours alone. PB is polished brass. AB is antique brass. AC is antique copper. SN is satin nickel. SC is satin chrome. CP is chrome plated. SB is satin brass. SP is bright polished. BN is black nickel. SS is stainless steel, and where a supplier distinguishes the two grades of it, SSS is satin stainless and PSS is polished stainless. Two more are sprayed coatings rather than platings: W and WL are white paint, and F is a wood-grain spray. Our own price list spells several of these out in its finish column (PB=Polish Brass on the 6094, SN=Satin Nickel on the 70710, SC=Satin Chrome on the 70610, BN Black Nickle on the 9211) and once you have seen the pattern once, the rest of the list reads itself.

A second group of letters is the function rather than the finish. ET is the entrance function, keyed from the outside. PS is passage: latch only, no cylinder, for a door that closes but never locks. BK is the privacy or bathroom function, with a turn button inside and an emergency release outside. So 607 PBBK is a 607 in polished brass, privacy function; 607 SNET is the same lock in satin nickel, keyed entrance. Read the letters from the right: the function comes last, the finish sits in front of it. 592 SSET is SS plus ET (stainless steel, entrance) not S plus SET, which is why reading left to right gets this backwards.

This matters commercially in a way that is easy to miss. A distributor who reads the codes stops quoting four hundred products and starts quoting sixty, each in the finishes their market actually buys. It shortens the range, shortens the conversation, and shortens the sample order, because a sample of the mechanism in one finish tells you what the other five feel like.

It also changes what you check before ordering. If the letters are the finish, then the finish is the part of the order most easily got wrong, and the part a photograph settles fastest. Ask for the finish you intend to order rather than accepting the one that happens to be photographed, and if a supplier sends the polished brass image against an antique copper line, treat that as a question rather than a detail.

One honest caveat about our own list. Where the finish column reads AB/AC/PB/SB/SS/SP/SC all available, that is the range the model can be produced in, not the finish of the piece in the photograph. A range in a specification is not a specification, and the two are worth keeping apart in your own records. A handful of older lines also carry a letter we have not confirmed the meaning of (S, E, D and a few others) and where we are not certain, our product pages say nothing rather than guessing.

The whole table, in one place

Prose is a poor way to carry a lookup, so here is the set we use. Most of it is industry-wide rather than ours; where a code is ours alone, it is marked.

Finish, the metal and its treatment

Function, what the lock does

The reversal trap, which is ours to own

Look carefully at the first table and you will find three pairs that are the same code written backwards:

PB and BP both mean polished brass. BN and NB both mean black nickel. CB and BC both mean bright chrome.

This is not a typo in one record; both spellings appear across the range, because they arrived from different sources over different years and nobody reconciled them. We are stating it here rather than quietly normalising it, because a buyer holding an old price list needs to know that BP and PB on two different lines are not two different finishes.

The same applies to black. BL, BRN and ORB all resolve to black in our data, and only ORB carries a distinct intent, oil-rubbed bronze, which is a black with a warm undertone rather than a neutral one. If black matters to the project, name the finish in words on the order and ask for a sample; the letters will not settle it.

Position beats letters

Here is the rule that makes the whole system readable, and it is the one nobody writes down.

BS is a finish code meaning satin. BS is also an order code on one cylindrical lock in our range, where it means something else entirely. Both are correct. The way to tell them apart is not the letters, it is where they sit in the string.

Finish codes sit at the end. Function codes sit before them. Digits (the actual mechanism) sit at the front. So the reading order is:

Read from the right and the string comes apart cleanly. Read left to right and you will try to resolve PB as a finish while it is still part of the model number. This is why our own parser reads position rather than letters, and it is the same method that works on a competitor's code, see our finish codes page for what to do when nothing resolves at all.

Four codes we have not confirmed, and will not guess

Four letter codes appear in our own model numbers that we cannot yet explain from a source: N, KT, IK and PT.

For each of them we have a plausible reading. KT beside DK looks like key-and-turn. IK appears on two cylinders only. We are not printing those readings as fact, because a plausible code definition is worse than a missing one, a buyer who orders against a guessed code gets the wrong part and has no way of knowing whose mistake it was.

If one of these appears on a list you are working from, send us the model and we will confirm it against the production record rather than the catalog. That is a slower answer and it is the only one worth having.

Why we publish the ugly version of this

It would be easy to print a clean table with one code per finish and no reversals, no duplicates and no unconfirmed rows. It would also be a table that stops matching the price lists people actually hold.

The codes on this page are the ones in our records, including the three reversed pairs, the three spellings of black, and the four we cannot yet explain. A buyer cross-referencing an old list needs the messy version, because the messy version is what is printed on the paper in front of them. A tidy table that silently drops BP helps nobody holding a line that says BP.

If you are building a purchase order from a list like this, the useful sequence is: identify the mechanism from the digits, choose the function from the third letter group, then choose the finish last and confirm it in writing against a photograph of that exact code. The first two decisions are engineering. The last one is the one that arrives in a container and either matches the door or does not.