In talking to Dave at TEP, he referred to the 15/16 as a mismeasured older 7/8. Anthony and some others can probably comment on it more, I believe the way the chains are put together is different, which keeps them from folding on themselves etc and makes them stronger.

Also..on the 1" there are two different versions. There's the 800hp set and the 1200hp set. The Ecotec guys started snapping the first version.