I was pleased with the performance of these shaker bottles. I was worried they would not stand up to the task. They serve their purpose, however. They do a good job of mixing the powder without any residual residue on the inside walls of the bottle. There is also no chunks of powder left in the shake itself. A+ for performance. They are sturdy & chic as well with no leakage from the caps during shaking (as long as you confirm the caps are fully locked down). The only issue I have with these is that the design makes them a little difficult to clean. Since the metal is more like a spring loaded slinky design rather than a loose shaker ball, it is a little harder to clean the lid & attachments. It is do-able, though & I believe this design works in favor of performance.