Why doesn't the number on my Promega product correspond to the number in the catalog?

Promega products have single or multiple components. Each product has a catalog # (Cat.#) and each component has a Part #. Therefore, all components have a Part #, but not all have a Cat.#. Catalog numbers are in the format of one (two, rarely) alphabetic characters, followed by 4 numeric characters (e.g., M1661 or MD1101). Part numbers are generally one (again two, rarely) alphabetical characters, followed by 3 numeric characters, followed by an additional alphabetic character (e.g., M166A or A712C). These Part #s are the numbers found on individual product tubes.

In all cases, parts that have the same initial letter and following three digits contain the same reagent, but may have different amounts of that reagent. For example, M166A contains 100 units of Taq DNA Polymerase^(a) and M166B contains 500 units. "M166" indicates that both products are the identical enzyme.

All of the products in Promega Corporation catalogs (both online and print versions) are listed by Cat.# only.  Nearly all parts have a distinct lot number and most catalog items have a distinct lot, which is different from the lot numbers on each of its parts. For instance, the restriction enzyme Bal I is Cat.# R6691, which consists of the enzyme (Part # R669A), Buffer G, 10X (Part #R007A), and Bovine Serum Albumin, Acetylated (Part #R396D). Each component has an individual lot number; moreover, the specific packaging of these component parts also has a unique lot number. Catalog items that are multi-component only, and which are not pre-packaged together, will not have a catalog lot number (but each of the parts will have its own lot number). 

^(a)Some applications in which this product may be used are covered by patents issued and applicable in certain countries. Because purchase of this product does not include a license to perform any patented application, users of this product may be required to obtain a patent license depending upon the particular application and country in which the product is used. For more specific information, please contact Promega.