PAI AN U-Cups are made to the dimensions of Military Drawing AN 6226.
Unit of Measure

Nominal I.D. (inches)

N/A 1 1/4

Nominal O.D. (inches)

N/A 1 5/8

Nominal C/S (inches)

N/A 5/32

I.D. (inches)

N/A 1.250

O.D. (Inches)

N/A 1.625