I'm not sure why GT made the traditional classics a heavier GPI? You have to lighten up on the broadhead to get a normal weight finished arrow. In general that means thinner blades, less length and sharper angle of approach, and weaker connections. There are exceptions. No need to argue the details or how someone won't even notice the slower arrow. Just saying it seems like the fad is stiffer, lighter shafts. I have not heard of anyone doing a revue on these yet. They should have sold a lot of them by now. I think the ID is .204. Same as Easton Axis.