This is 100% necessary for me to make smoothies every morning. I put my milkshake and coconut milk into the shake bottle mixer of the blender, shake it, and then add the rest of the milkshake ingredients to the blender. Then I took out the juicer ball from the shake bottle mixer, then poured the mixed smoothie mixture back into the juicer shake bottle mixer, and drank it on the way to work. It was not spilled in my bag.
I always think these are expensive, but after trying other cheaper shake bottle mixers, it is a good choice to spend more money to buy an ergonomic shake bottle mixer specially designed for mixed supplements. If you want to avoid the common top falling problem, make sure you tighten the cap from the bottom, not from the drinking tube.