The Focus ST actually is a separate model in our system (you’ll see that you can select it separately in the model list). However, unfortunately, based on how things are currently coded, the ST will sometimes show up for regular Focus searches. Unfortunately that’s non-trivial to solve generally, but it is something we’re working on.

That said, if you want to avoid Focus ST results in your search, there is a way to do that – in the keywords field (under Advanced Search) enter -ST. That will tell it to exclude any results containing “ST”. So unless there’s another reason that word would appear in posts you are interested in, it should solve your problem. (And again, we’ll keep working on the more general case.)