Hey Jack, Matt @ Maximillians just called me and pointed out that I ordered 13 54 1 307 766 which is the single Large "o" ring and what I really wanted was 4 small "o" rings which are p/n 13 54 1 307 768. The last number should be an "8" in order for you to get the small ones - so change your order. I checked my HTK and he was absolutely right..