when getting my supertacks I tried on the Ultratacks in both the 6 and 6.5. The 6 felt a little tight especially in terms of width where the toebox is attached to the rest of the boot. Since I was told that in the Supertacks that I would have to go up a 1/2 size, I got the 6.5 Supertacks ordered for me and they fit perfect. For reference I was in a 6.5 D APX2 with the big toe area of the toebox punched out a little on my left skate, while I fit fine in a 6.5 D Supreme 1S without having the toe box altered. The Supertacks for me were perfect and even better after baking, no pressure points and would say that for me atleast the heel lock has been the best I've ever had.