Doesn't Seal Very Well
I bought four of these to use for protein shakes.  The caps do not seal very well.  You cannot transport drinks in them because the caps can easily come off.  Also, when shaking my drinks they often leak out around the cap and shake all over the place.  Any pressure around the outside of the cup (such as your hand when shaking the cup) will break the seal and cause leaking.<br /><br />Update:  I am having better luck with these now after learning to not hold the sides while shaking them.
Rating: 2 stars