Difference Between TR2 and TR3 Small Mouth Front ?

[Jim Shaw <jimboshaw@compuserve.com>]

Having both aprons here to look at, the best way to tell a 2 apron from a 3
is look in the mouth. If it is fully enclosed inside it is a 2. If it has
an opening in the top of the mouth it is a 3. Why they changed  I don`t
know. Hope this helps. Jim