Bought a 500ml series 2, the cap leaks every time it’s opened. They sent a replacement cap and that also leaks. The neck also stains if you drink anything other than water (e.g squash), and the two neck components regularly screw off together which is very annoying. They sent a rather condescending response about ‘how to hold the neck in place’, as an adult with common sense I understand this, however having two components where you need to screw/ unscrew will always create this issue. Really disappointed about this, we have 4 series 1 bottles and no issues with these. The series 2 is a poor design, over-engineered and I will not be purchasing again.