The OP can clarify but I think he's referring to the o-ring that holds the cap on, not the one placed in the base of the catch cup.
Regardless, they're the same size. 1mm thick, 10mm I.D. They also fit the base of the Cyclone
rda.
Of course, Rob also sells a larger size for the catch cup... 1.5mm CS x 10mm I.D. if I recall correctly.
Cheers