We pride ourselves on continual improvement, but it is going to be tough to make a lighter sack than this without utilizing some sort of antigravity technology. Absurdly light—less than ½ the weight of a comparably sized sil nylon sacks, these roll top bags are waterproof, and have 3X the tensile strength of sil nylon. Made of a material originally used as sailcloth on World Cup sail boats, the Überlight CTF3 sacks set the bar for ultralight storage.