Small (6/7) 265mm
Medium (8/9) 278mm
Large (10/11) 299mm
 
The TNEC 58 was made to be the absolute best price point skate on the market. The main focus of the TNEC 58 skate is to create the absolute best option for people getting into aggressive skating. This skate is strongly recommended for ANY and ALL beginner - intermediate aggressive skaters
The TNEC can be a great skate for advance level skaters as well depending on your preferences.
Unique Features  Include:
Universal fitting boot mold
Flat 58/88a wheels
One Piece soul/frame
Neoprene toe liner
Non UFS
Fully riveted components
Lightest 
Aggressive skate on the market
Internal Shell Measurments: (give or take a few mm depending on where the shell is measured, not measurement is ever 100 exact)
Internal Shell Sizes
Small (6/7) 265mm
Medium (8/9) 278mm
Large (10/11) 299mm
The skates fit true to size. A good indicator is for getting the correct size is knowing what size THEM skate you ride.  (ie if you ride a 7 them get the Small 6/7 TNEC boot)