It did have a membrane. Until someone threw it in the washer because it was a little dirty and stinky. Unfortunately the most I could probably get in the bag now is the razor blade. The pack I carry has medical, clothing, fire and survival gear but it never hurts to have extras. Thanks Les.

I'm with Izzy on signal mirrors - real signal mirrors, not the improvised items. They are well worth the miniscule increase in space they require over the improvised items you are listing.

My experience with them in sunny Arizona and California has turned me into a true believer for the real thing. And there are some very nice, extremely light models out there.