Amazon.com: FITLY Soft Flask - 8.5 oz (250 ml) - Shrink As You Drink Soft Water Bottle for Hydration Pack - Folding Water Bottle Ideal for Running, Hiking, Cycling, Climbing & Rigorous
250/500ml Foldable Silicone Soft Flask Water Bottle Outdoors Camping Traveling Sport Running Jogging Hydration Bladder Pack Vest - Water Bottles - AliExpress
Salomon Soft Flask 250ML / 8OZ - Walmart.com
Salomon Soft Reservoir, Soft Flask XA Filter – Gravity Coalition