Unlikely they have a mute but because it is a trade in store, call in and check. They may just have one.
Though the trumpet selection is not large at all, they do offer some used and new models; but if you are going there purely for a trumpet, I would call ahead to see what their current selection is. On the other hand, they have a large amount of guitars, keyboards, and a beautiful stocked drum room, and have used and new options in all of their instruments!
They do have some brass instruments in the back area. Should be able to handle most needs. Give them a call, they have multiple locations too.
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