BPS is right I'm pretty sure they're all one size.My remington star-dot is .670.The .676 for the star-dot is good for any size.You won't be disappointed in that choke.If you don't plan on shooting past 50yds shoot 3.5" WIn HV 5's.If you are shooting past 50 use the 3.5" Win HV 4's.I'm just not a fan of 6's,but they pattern great also.Hope I helped!
Campo when you shoot it,pm me and let me know how you like it.