I got the AZ-EZ in rt hand helical on the advice of Danny Miller. I believe AZ's rt hand helical is 8 degrees. Somehow, I don't think that is the same as offset, as I can barely tell the diff in factory fletched or mine. I've done 2" Blazers and 4" Dura vanes w/ no clearance problems I'm aware of. I've gotten some remarkable benched groups w/ Blazers. Somewhere on Excal forum is a 4 part video on using the AZ. The previous info on needing the alum model for xbows was spot on.