Hydrapak soft flask 250 collapsible gel flask 250 ml description nutrition on demand the sf250 collapsible gel flask can be integrated into a variety of packs vests pfds and lumbar belts lightweight flexible and easy to squeeze the softflask tm collapses as you drink eat as much as you wish per use and throw in the fridge for later the patented spill proof self sealing bite valve is easy to use and completely removes for cleaning designed to carry gels water electrolytes o