Inner frame size:

Note that it is plexiglass!

Square (inner diameter 10*10) no tenon

Square (inner diameter 15*15)

Square (inner diameter 20*20)

Square (inner diameter 25*25)

Square (inner diameter 30*30)

Square (inner diameter 40*40)

7 inches (inner diameter 12.7*17.8)

8 inches (inner diameter 15.2*20.3)

10 inches (inner diameter 20.3*25.4)

A4 (inner diameter 21*29.7)

8K(26.5*38)

4K(38*53)

16 inches (inner diameter 30.5*40.6)

18 inches (inner diameter 35.5*45.5)

Frame size:

Regular