Tuning doubt about FX orings list

[josepartida]

I am looking to have a stock of orings for my fx crown but looking at the oring list I am unsure about it as it does not specify if the measurements are internal or external.

 

[Centercut]

FX lists ID x CS

Internal Diameter by Cross Section (thickness)

Some oring stores list CS first. 

 

[josepartida]

excellent you save me from making a mistake thanks

 

[Centercut]

De nada