I ride a DiamondBack Release 4C which has an under down-tube bottle mount. During some recent rides, the TWIST connector broke off of the bottle. The center key that you turn to install/remove it broke such that it wouldn't stay on the bottle. I have the 590 (oblong type) bottle. Anyway, I emailed FIDLOCK with pics and proof of purchase and they sent me a replacement connector under warranty. The replace said it was a "gravity" version, which I don't see on their site. It includes an ingenious new ultralight metal strap the help hold the bottle and connector together. But, it seems like they made it for the round 600 version bottle. It was an extremely tight fit! In the end, I had to super glue the included tiny nut into the connector so it would stay in place. Then, with my wife helping, we had to really contort the bottle so the strap would reach all the way around it and could be screwed in to the now-super-glued-in-place tiny nut. Ok, this review is probably hard to visualize, but if you get the gravity connector and try installing it on the 590 bottle, you'll understand. I'm knocking 1 start off because I believe the strap should have been about 2-3mm longer for the 590 bottle. But, it is definitely on there tight! Also, I added lock tight to the screw to keep it from vibrating loose. Love my fidlock system, but install for the gravity base was a pain!