bottlepro - adjustable cup holder adapter, compatible with 32/40 ounce hydro flasks, iron flasks, takeyas, simple modern, nalgenes, fifty fifty, thermoflasks, klean kanteens bottlepro bottlepro was designed for bottles that are approximately 3.5" to 3.8" across and have straight-vertical walls. compatible with hydro flasks (32/40 ounce), nalgenes (32/48 ounce), yeti rambler bottles (36 ounce only), klean kanteens (32/40 ounce), and many other large bottles. bottlepro is not very compatible with tumbler-style bottles that get smaller towards the bottom, including 30 ounce yetis. also is not compatible with 14oz yeti mugs. important, please read. there are thousands of possible cup holder and bottle combinations, and bottlepro will not work for every single situation. if bottlepro doesn't work well for you, please contact us directly for an easy hassle-free refund. we're easy to work with.