Blum makes an excellent product; that's why I ordered a set of 12" undermount drawer slides for a very specific need. Unfortunately, the supplier, Woodworkers Hardware, sent me a set of drawer slides for a 21" drawer length.Somebody's dyslexic? I don't know--but everything was marked 12"--in the order, receipt, and the packaging. All I can say is, the actual length certainly doesn't match a 12" description. I haven't had time to make a return of the item, so I can't yet describe the Customer Service response.