This practical design allows you to carry your BUILT water bottle/travel mug when you're on the move, totally hands free. These bags feature adjustable shoulder straps. There's even a handy mesh pocket on the back for smartphones and other important little items. BUILT's bottle carry bags are made of 100 per cent polyester with an insulating polyethylene core and 100% PEVA food safe lining. Place any standard-size sports bottle in one of these carriers, and it will help keep it warm or cool.