Every ANSI/BHMA standard contains an explanation of the BHMA® product numbering code applicable for that particular category of hardware. BHMA® product numbers utilize a five-digit number preceded by a prefix letter:
The prefix letter denotes the BHMA Product Section that produces the hardware.
The first numeral designates the base material for the product. BHMA standards use the default number '0' to allow the manufacturer to use an optional material that meets the performance requirements of the applicable standard.
The second number identifies the type of product.
The third and fourth numerals identify the function of the specific item.
The fifth number indicates the performance grade of the product.
Every ANSI/BHMA standard contains an explanation of the BHMA® product numbering code applicable for that particular category of hardware. Using the example above, a specifier would refer to the ANSI/BHMA Standard A156.9 for cabinet hardware, and ascertain that for product B 5 2 1 3 1...
B = Product Section for cabinet hardware hinges
5 = Stainless steel
2 = Cabinet knob
13 = Back mounted
1 = Grade One
Thus the product is a Grade 1, back-mounted stainless steel cabinet knob.
Note: Explanations of the number codes applicable to this category of hardware (e.g., 13 = back mounted) would be found in the 156.9 ANSI/BHMA standard .
Building hardware products should always be specified by BHMA® product number to eliminate any confusion over brand names, performance standards or product grade.
Link here to find out 'What the Numbers Means' for selected ANSI/BHMA Standards.