aimless, I've only used 'em in "squeeze mode". for me the trouble seems , most often from storage (between outings_). brand new they seem to hold up great..but trying trying to use one after storage, it's either bad on first attempt or shortly thereafter-for the record, I'm a "fair weather" hiker-no overnight freezing temps...it's not like I'm totally bummed out, since this gives me the motivation to try chemical treatment and allows me to reduce pack size a wee bit.