This is a follow up on my post about rucksacks. I'm following the path of Michel Blomgren and would like to get the rucksack's best friend, the military poncho. He says it's the only shelter he brings even during normal outdoor activities. I think he uses a poncho that has a rubberized coating for maximum waterproofness and it has grommets. I think some call it a gum blanket. I'm aware that condensation may easily form but I want it for it's maximum waterproofness in rare heavy downpours and to use as the main expedient shelter as he does.

Do you know a reliable source where I can get them?

Thank you.