Love Fidlock design as a whole but this review is for the 600ml bottle. The bottle is well constructed and sturdy. The “gravity strap” probably helped with stiffness but is a real pain to install. Also, when you take a sip, the bottle only allows so much fluid to exit the nozzle before the back pressure stops the flow, forcing you to stop drinking and allow the bottle to suck back in ambient pressure and then start again. This issue alone loses a star. The other being that it has no nozzle cover like the 590. If I were to buy a spare bottle again, I’d go with the 590.
