HydroFlask Standard Mouth Flex Straw Cap

Some lids make drinking easier. The HydroFlask Standard Mouth Flex Straw Cap makes it genuinely effortless — flip to sip with one hand, close securely for leak-proof transport, and carry comfortably with the integrated Flex Strap. The simple upgrade that transforms your Standard Mouth Hydro Flask bottle into an on-the-go hydration tool you can use without putting down whatever else you’re doing.

Hydration on the go just got easier with the leakproof, insulated Flex Straw Cap. Add it to your favourite Standard Mouth Hydro Flask bottle to easily enjoy cold hydration anywhere.

Key Features

• Fits all HydroFlask Standard Mouth bottles — check your bottle’s mouth type before ordering; Standard Mouth has a slim opening with internal threading, Wide Mouth has a wide opening with external threading
• Honeycomb Insulation™ — insulated cap for maximum temperature retention; keeps your drink colder for longer by reducing heat transfer through the cap
• Leakproof when closed — flip the straw down and the cap seals reliably; carry in a bag, jersey pocket, or backpack without worry
• Flex Strap — integrated flexible handle that doubles as a carrying loop; comfortable to grip and easy to transport one-handed
• Straw is easy to trim to fit your favourite Hydro Flask
• BPA-Free & Toxin-Free; Removable components for easy cleaning
• Dishwasher safe — remove components and place in the dishwasher for a thorough clean
• Weight: 75g / 2.72oz
• Also compatible with Small Flex Strap Packs
• Not intended for use with hot liquids or carbonated beverages

Standard Mouth vs Wide Mouth — Which Cap Do I Need?

The Flex Straw Cap is available in both Standard Mouth and Wide Mouth versions — make sure you order the correct version for your bottle:

If unsure, check your bottle’s product listing or measure the opening diameter — Standard Mouth is approximately 44mm, Wide Mouth is approximately 60mm.