I just recently bought my very first Surly single speed cog.
It came with a very eco-friendly package (recycled cardboard printed with soy ink??) but I just had to laugh when I read the legal disclaimer inside the packaging... so when did lawyers start using "cool english" of the sudden, instead of legal gibberish? I kinda like it, it's refreshing.
Here are a few excerpts:
Please read all these instructions before you...
... our trusty legal counsel compels us to point out that if this installation isn't done properly, YOU COULD DIE riding your bike, which would make us sad.
What this warranty doesn't cover is damage resulting from any sort of riding other than "normal"... we're hip to the "just riding along" phenomenon - and frankly, we're just not having it.
Lastly, if you modify or neglect your cog or lockring we can't be responsible for the product or what might happen to you while you're using it. We hate to spell it out, but hey, it's the 21st century.
BTW really well made cog, it's really stiff too. I bought a 20T because the one I pinched from a 9speed cassette was flexy when being hammered and prone to shifting - OUCH!! My chain "pulse" also disappeared because this thing is just perfectly centered. Real happy with it... except for the price... but quality always has a cost I suppose.