£1.60 for a bottle cap coz thats all they are, personally I think they have out priced themselves from the market as it is only made up from plastice, rubber and a spring.
If they had gone to around 50p a cap and buy them in bigger bulk them the concept may have taken off. The website also sells spare parts for the caps so they mustnt last too long before they need repairing and they must be a friggin nightmare to sterilise with all the sediment at the bottom of the cap.
And for those reasons "I'm out"