Don't feel bad-we never knew we needed an insulated double wall capacitor stainless steel water bottle, either. That epiphany came after a moab trail run when we got back to the car, windows rolled up tight in the blazing late-august sun. Reaching through the 150-degree blast furnace, we grabbed the free flow ss off a leather seat so hot it could fry an egg, and took a sip of water so crisp and cool, it seemed like a miracle. The free flow's rapid-pour, leak-proof AUTOSEAL locking lid with its easy-to-clean drop down lid feature fits all sizes of our capacitor stainless steel bodies. Features aside, it's the powder coated, dishwasher-safe double wall design keeping your water cool and drinkable all year round that will change the way you think about hydration.