That is the beauty of that barrel. It can shoot any size paint. The main part is .693 but with the sizers you can shoot small paint too. I shot Proball Platinum out of a OTP G-1 with the green sizer, sometimes the blue. It was very consistant over the chrono, and very accurate on the field.
I would reccomend this barrel to any cocker or shocker owner, because the sizers prevent rollout.