SK stands for Survival Kit, but this tool doesn't have either an 8mm Allen key or a torx, so if you were considering buying the SK we'd recommend forking out for those two extras in order to be truly selfsufficient out there.
It's worth considering the SK, though, because it's well made and the tools have excellent tolerances. It comes with a patch kit, plus a bag that fits the tool perfectly, so it doesn't rattle around. If you were going to buy a bag anyway, then it makes the SK look like pretty good value for money.