Hydration on the go just got easier with our leak-proof, insulated Flex Straw Cap. Add it to your favorite standard mouth Hydro Flask bottle to easily enjoy cold hydration anywhere FEATURES: Honeycomb Insulation(TM) - Insulated cap for maximum temperature retention Leakproof - Reliably sip and transport your refreshment without worry Easy to Clean - Removable components for easy cleaning Flex Strap - Easy to transport; comfortable to carry