I clicked on the link for the EGR valve that you posted and what I did was read the review for the part that a previous purchaser had posted. My guess is that the large o-ring/seal is what you put between the EGR position sensor and the EGR valve it self. The reviewer that that they have no idea what the smaller o-ring was for. I think my BWD replacement came with the same thing but I can't find anything in my repair manual that mentions a smaller o-ring. Also, the EGR position sensor, if you decide to replace this part, also comes with an o-ring seal. Maybe call American Muscle and ask them?