The Boulder is our flagship bottle that enjoys wide popularity, especially with its updated slimmer body and sleek profile. You can fill this bottle with both cold and hot drinks and take it anywhere, since its secure top will keep your drink inside where it belongs. So, toss in a tote bag or backpack and hit the trails, golf course, run errands around town or keep on your desk for convenient hydration through the day. – This bottle features our vacuum TriMax® triple insulation technology and has been tested to keep liquids cold for 36 hours and hot up to 8 hours. Its dual use leak proof top has a wide opening for easy filling and a small opening for easy drinking. A versatile vessel for anything, anytime, anyplace and now available with interchangeable tops!