The Maurten Gel Mix Flask 350ml pairs directly with their Gel Mix 480. The sachet opening matches the flask's fill point, so pouring in the powder skips the spills a mismatched container invites. A SpeedFill cap opens fast for mid-ride refills, and the bite valve lets us drink without unscrewing anything first. At this size, it fits a running vest, waist belt, or back jersey pocket without adding bulk. What Our Gearhead(R) Experts Are Saying:"I clip this to my vest for anything past three hours and forget it's there until I need it. The bite valve lets me drink mid-stride on a rocky descent without breaking my grip on the poles."