Hydro Flask Medium Bottle Boot Black. Specifically sized to fit our 32 oz and 40 oz Wide Mouth bottles. Specifications for Hydro Flask Medium Flask Bottle Boot: Manufacturer: Hydro Flask Color: Black Size: Medium Gender: Unisex Age Group: Adults Features of Hydro Flask Medium Flask Bottle Boot Fits 32 oz and 40 oz Wide Mouth bottles Removable silicone boot adds extra protection to your Hydro Flask bottle BPA-Free Dishwasher safe Not for use on a stove in a microwave or freezer Package Contents: Hydro Flask Medium Flask Bottle Boot Hydro Flask BBM001: Medium Bottle Boot Black