Made to fit perfectly in all of our hydration vests, the Restrap Soft Flask packs in a 500ml carry capacity into a collapsible bottle with a twistable, angled bite-valve. There’s even a locking nozzle to prevent unexpected leaks when not in use. The flexible MPE bottle is form fitting when full and packable when empty, making them the ideal solution for stuffing into the front pocket of a vest, or slipping them into the back of a jersey pocket. READ MORE. Soft Flasks are perfect for dosing out sports fuel and are much easier to keep track of how much you are drinking than a hydration bladder. They also pack down smaller than a traditional bottle, with the added bonus of no sloshing when they are part-full. Chuck one in your bikepacking kit for the “final mile” before camp, or use it as a minimalist carry for a blast in the woods after work. Whatever your desired use, the Soft Flask is your flexible friend in both senses of the word.