An invoice, a key list or one of our product titles reads 1A1A1KS473KS800, 1A2A2 or 1AP1WB1KS609KS800, and before you reorder you need to know what it is: a blank or a cut key, an everyday key or a control key, Standard or Premium. BEST builds these numbers field by field in the How To Order for its Standard and Premium keys, on page 15 of its parts and ordering list PL78 (August 2026). Its Key and Core brochure (BA-0232) draws the stamps and the parts of a key.
How to read a BEST key number
The How To Order sets out six fields in this order: key shape (the bow), key type, keyway, cut code, key stamp and options. Here is 1A1A1KS473KS800 taken apart:
| Code | Field | Meaning |
|---|---|---|
| 1A | Key shape | Standard |
| 1 | Key type | Operating or blank |
| A | Keyway | A keyway |
| 1 | Cut code | Blank, not cut |
| KS473 | Key stamp | Standard front stamp |
| KS800 | Key stamp | Second stamp code |
The same reading works on our other titles. 1A1K1KS208KS800 is a Standard blank in the K keyway with the KS208 stamp. 1A1A2 ends in cut code 2, which makes it a cut operating key in the A keyway, and 1A2A2 is a cut control key, type 2, in the same keyway. 1AP1WB1KS609KS800 is a Premium blank with WB in the keyway field and the KS609 stamp. Words that follow the code in some of our titles, such as Kit or Green, are not fields of the How To Order.
Key shape, key type and option codes
Key shapes, the first field:
- 1A: Standard
- 1AP: Premium
- 2A: large round
- 3A: large rectangular
- 4A: access bow
- 9A: blockout blade
Key types, the digit after the shape:
- 0: blockout blade
- 1: operating or blank
- 2: control
- 3, 4 and 5: master, submaster and grandmaster
- 9: extractor key
The cut code is 1 for a blank and 2 for a cut key. Options come last: B for a long blade and N for a long nose (both 1A only), H for no hole (2A only), NKW for no keyway designation, which is standard on 1AP keys, and S for key serialization.
Change key or control key: what the type digit tells you
PL78 does not use the term change key. Its type 1 covers operating keys and blanks, and our 1A1A2 card calls that cut type 1 key a change key. The control key is type 2, so 1A2A2 is a control key cut in the A keyway. The number names the kind of key, not the combination it is cut to: for cut keys PL78 also asks for the keymark and the number of keys of each marking.
The brochure's drawings of a core mark two shear lines, one for the control key and one for operating keys. BEST describes what the control key is for when a key is lost: remove the core with the system's control key, insert a new core, issue new keys and update the records. Our SFIC and LFIC guide covers the core, its housing and core numbers such as 1C7A2.
KS stamp codes on BEST keys
The KS numbers are BEST's key stamp codes, the marking on the bow, and PL78 asks you to specify the KS number when you order. The Key and Core brochure defines five front stamps:
| Stamp | Keys | Use |
|---|---|---|
| KS473 | Standard | Standard front stamp |
| KS208 | Standard | Alternative front stamp |
| KS567 | Premium | Standard front stamp |
| KS609 | Premium | Alternative front stamp |
| KS594 | Premium | Alternative front stamp |
In the brochure's drawings all five carry the BEST name. KS473, KS208 and KS609 add the words "DUPLICATION PROHIBITED", and KS473 is the one framed with stars.
PL78 lists KS567 simply as Premium and adds two entries the brochure does not draw: KS654 x KS292, the BEST logo with full embossing and stars, for 1A and 1AP keys only, and KS112, "U.S. Gov't do not duplicate". Our blank titles such as 1A1A1KS473KS800 end in a second code, KS800. Neither document defines KS800 for Standard or Premium keys, so we read it only as a stamp code.
Standard or Premium: which key goes with your core
The comparison table at the back of the Key and Core brochure pairs each key with its core: the Standard key with the 1C Standard core, the Premium key with the 1CP Premium core. The brochure's Key Types page says it outright for Premium: the 1AP is for use with the 1CP core. The keyway has to agree too, as our key blank guide explains for keyways in general. In a core number such as 1C7A2 the keyway is the A after the pin count, and in 1A1A1 it is the A after the key type. PL78 also lets the keyway field name more than one keyway when you order a multi-milled key, and the brochure's comparison table checks multi-milled keys for Standard but not for Premium.
The two keys are built differently. BEST calls the Premium blank its thickest, larger and heavier than a Standard key, with a paracentric keyway in which the keyline crosses the center of the core. The comparison table gives the key material thickness as 0.145 for Premium and 0.097 for Standard, and counts 8 Premium keyways against 29 Standard ones. In the same table the large round bow (2A) and the access bow (4A) are checked for Standard keys and not for Premium.
One core detail changes the key. PL78 marks the 2C core for the 8L mailbox and the 5C high security core as needing a long blade key, and the long blade is option B, offered on 1A keys only.
Markings on a BEST key
BEST's Key Anatomy picture names the parts: the bow with its chain hole, the blade with its keyway milling, the cuts and the key stop tip. It also points to three markings. In that picture the keyway designation is marked on the blade next to the bow, and the series keymark code and the serialization code are on the bow.
NKW, standard on 1AP keys, leaves the keyway designation off, and S adds the serialization code.
BEST keys at The Builders Supply
Our BEST blanks and cut keys are on the BEST brand page and in key blanks and keys, and the examples read above are listed under this post. Compare shape, type, keyway, cut code and stamp with your own number before you order.
Not sure which blank, stamp or control key matches your system? Our customer support team is available Monday - Friday, 8 AM - 4 PM Central Time, at 1-888-800-7789 or [email protected].
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