I must say, I had no idea that's what they were called, until I Googled it. Very interesting, and I HAVE seen them before, in their use as a grousing contact. Never seen them of any of the other uses they mention. Pretty interesting product - the web site has a complete history and information on how they are made.
BTW according to the web site, 100 mil is not a standard size. They go from 90 to 125. 100 would be a custom size.