There are at least two types for the Snow Tracs that I am aware of.
The first photo is one of my tracks, they are similar to the first two photos of the Thiokol grousers posted in that they taper toward the ends and are deeper in the middle. These also have "tabs" for preventing lateral sliding and they run right down the center of the track.
The second photo shows a Snow Master track, but I've seen the same set up on some Snow Tracs as well. I'm bet these are better at preventing lateral slides and for cross slope travel. The Snow Master is a wide track & long track version of the Snow Trac. The Snow Master is really a snow only machine and trying to turn on the grass will walk the unit right out of its tracks, while I can drive my Snow Trac on the grass (despite my wife's objections
) without tearing the tracks off the unit.