No 5
4 5/8"
No 4
75mm or 3"
No 3
67mm or 2 5/8"
No 2
54mm or 2 1/8"
No 1
48mm or 1 7/8"
O
32mm or 1 1/4
OO
16.5mm (or 19mm USA)
HO
16.5
TT
12mm
OOO
9mm
N
Z
6.5mm
