The HydraPak Flux 1L – A Smartwater Bottle Replacement? Sep 25, 2020 by Andrew Marshall The HydraPak Flux 1 L (2.7 oz / 77 g, MSRP $20) is a soft-sided, collapsible, 42 mm threaded, reusable water-bottle aimed at the single-use Smartwater or sports-drink bottle crowd.