How to steralise nuby rapid cool?

[MommyRainbow]

What methods do people use?
Nuby website says to use UV steralisation or cold water steralisation.
We have Milton tablets and they say to not use on metal so I'm not sure what to do.
We have a Large UV steraliservand although good for the lids, I'm not sure either works for the bottles due to the shape of the bottle and the machine.

I use Milton cold water, the liquid Milton. I wash them in warm soapy water after using it then dunk in the Milton till I need it again!