This is an Orioles sleeveless home alternate, it replaces the home bp jersey. The Orioles "O" on the left chest, and Braves-style piping. No names on the back, just numbers, for that retro look. It's made up, they don't actually wear these, but honestly, I think they should.
NOTE: if you want the orange bill on the helmets, change the file name to uniform_bao_bpa so it replaces the road bp jersey. Home helmets are all black, for some reason.