The higher the first number , i.e, TB5 , TC7 etc, the higher the difficulty level or rather the lower the handicap or more accomplished player they're intended for. So TC7 are aimed at a scratch or lower cap guy and the TB5's would be aimed at higher handicap. That's with irons, not sure about wedge numbers. https://www.fourteengolf.us/collections/frontpage About halfway down it talks about sequencing , 3 , 5 , 7 . Having said all that, I played the TB-7's for a bit and thought they were super easy to hit .