Float seat o-ring measurements

Hello all,

I am wondering if anyone has specific measurements for the o-ring size on a 1980 xs 400 special. I ordered a pair from here (http://www.ebay.com/itm/171133926363) and they were far too large for my float seat so I do not believe what I have been reading online regarding the sizing for these o-rings. I have a picture attached. From left to right is the original o-ring (whether it is an edged or worn old rounded o -ring i cannot tell), the o-ring from that ebay purchase and the float seat it need to be put on. Any help would be appreciated. It can't be that outrageous to get the size of this thing.

Best way is to buy new needle/seats as a set. It comes with the proper seal

Those are the ones I have used on at least 6-8 sets of carbs. Use a little grease on them and they will fit snug tight in the carb. Remember the valve needs to be fuel tight.