AquaFlask Small Replacement Cap Insulated Water Bottle Replacement cap for 16oz AquaFlask Insulated Double Wall Stainless Steel Water Bottle with Handle DESIGN UPDATED AUGUST 2018 - Guaranteed to fit all 16oz AquaFlask brand bottles Only fits 17oz and smaller S'well brand bottles (excluding S'ip by S'well). DOES NOT FIT 25oz Swell bottles. May fit certain other brands, but we cannot guarantee a proper fit as this is manufactured specifically for AquaFlask bottles. See our other AquaFlask Cap listing if you need a cap that will fit 25oz bottles (large Swell size). This is manufactured by AquaFlask and is not affiliated with the S'well brand.