CD - yours could be a 21E - Viking used a combination of the "names" Viking/Husqvarna/Automatic and the logo in different locations and typeset on these machines, does not seem like a real rhyme or reason to it . . . When I was looking online, all of those that said Automatic were either 21 or 21A - but that does not mean there isn't a 21E with it on there . . . I didn't look at "all" of them. It's not really an issue unless you are looking for something like the tensioner - the bad part, they "look" similar, but key parts are different that make it so they won't fit and/or work on the other machines.