Help with oil return tube O-rings
 

I'd like to replace the O-Ring located in the oil return tube which can be removed when performing an oil change, but I'm confused as to the proper O-ring(s) to get. PET call for two different sizes.

PET specifies 2 oil rings of size 21.89 x 2.62 mm (part #999 707 316 40). Where do *2* O-rings go? I can see where one of them goes but not the second.

Also, why is a second oil ring size, very different from the first, called for? It's part # 999 707 309 40 and the size is 26 x 1 mm. Larger in diameter but much thinner.

Thanks everyone and happy new year.

Thanks Kim. So is the reason the thinner o-ring is called out in parentheses in PET is bacause it is not shown in the diagram. Is that the PET notation for 'not shown'?