@DXR I saw your post back in the day & put it in the memory bank. Picked up a couple of the back bottle the other day. I THINK THEY ARE GREAT! One of the problems that kept me from riding with a bottle in my jersey pocket as part of my hydration solution is getting the bottle in and out of the pocket. My kit is pretty aero so the pockets aren’t as slack. It’s hard to get the bottles in after drinking. This sure solves that problem. So a couple of these bottles is an easy way to carry a little over a liter of water w/o dealing with a hydration pack or bottles on the frame. Simple and easy.
Definitely easy in and easy out of the jersey pocket. And doesn’t bounce out when you hit some rough stuff.
They come with a ‘freeze line’. 
So you know exactly where to fill if you’re going to freeze them. And, oh lordy, does it feel nice having a couple of frozen backbottles in your jersey pockets on a >90F day. They’re kinda flat on one side so you get this big cold contact point. Very nice.
Not for everybody but it’s a pretty good solution. Not a paid endorsement. I don’t know who makes these. Just think it’s a clever/effective idea.