Only thing I'd suggest about that is it doesn't look easily resizeable, if you find the need to stick a different size bottle in there.

Not made anymore, but I actually bought every one of these they had in stock when they went on the discontinued rack at REI, I like them so much. They hold bottles well, look sleek, and easily bends to accommodate any (reasonable) size bottle. Ran over miles of cobblestone without any issue, although I'm not sure I'd use them in an under downtube application. Dunno if anyone else makes something similar, but if they do I highly recommend. Bonus is they are fairly lightweight.

https://www.rei.com/product/881259/n...er-bottle-cage