Mix it Smooth – Every time! The patented Blender Ball found within the bottle ensures thorough mixing and a lump-free shake, meaning you get the same consistency every time. Features Rounded base Spoutguard design to keep drinking spout clean Dishwasher safe BPA and Phthalate free Benefits The patented BlenderBall wire whisk is the secret behind the BlenderBottle's power. Add your ingredients, drop in the BlenderBall, and shake.The BlenderBall whips around inside the bottle, mixing your drinks to a smooth and lightconsistency every time. Made of 316 surgical-grade stainless steel, the BlenderBall is designed to remain in the bottleuntil you've enjoyed its contents. Just drinking water? Feel free to leave the ball inside - it'll neverrust, chip, or peel.