Shaker bottles are most commonly used to mix protein shakes, and can also be used for all manner of other things.

and supplements Patented mixing system uses 316 surgical-grade stainless steel BlenderBall wire whisk found only in BlenderBottle brand shaker bottles Screw-on lid creates leak-proof seal ...

A capped 2-liter plastic bottle containing a clear, colorless liquid is shaken. The liquid turns a deep blue color. At rest, the liquid returns to colorless. The cycle can be repeated many times. Ask ...