Shake, Shake, Shake it!

this shaker did a very good job in terms of mixing protein powders, even when making really thick shakes.
the blender ball inside did a good job of keeping shakes smooth and even. it can double as a water bottle without leaving protein taste lurking in the plastic.

the twist seal is very tight as well as the white cap on top, so you never have to worry about it spilling out of the edges or top of bottle while you're shaking it. The ONLY frustration (and reason why it was a 3-4 star product IMO) is that the purple twist top cracked on me. In this particular case, I only had the bottle for a little over one month and I was intentionally gentle when handling it because a friend warned that it had happened to him. It was only $8 so not the biggest loss ever, but still very disappointed that it didn't hold up very long.