The BlenderBottle® Classic is the #1 best-selling shaker cup for a reason – it works. The patented BlenderBall® wire whisk whips around inside the bottle as you shake, mixing even the thickest ingredients with ease.
The bottle can be stored even if the glass is filled to the end of the cup. Measurement marking ends at 20 oz for aesthetic reasons. For example, a 28 oz water bottle has a scale of 20 oz, but its maximum capacity is 28 oz.
If you are not sure about the size, please buy one size larger. For example, if you are asked to put 16 oz of water and powder in your shake, you can buy 28 oz to mix well.