This is not a very good product. I was really excited to get it, as it's quite annoying to try to properly clean my water bottles and coffee thermos, but this didn't work very well and it was messy! The bristles are very stiff, so every time I pulled it out of the bottle it sprayed soapy water all over me and the counter. And regardless of how much I scrubbed I couldn't get all of the staining out of the thermos, which was my main reason for buying these.
The brush that is supposed to be for cleaning the caps is too big to properly clean the toddler water bottle cap and I couldn't use the straw brush for that as it has no bristles at the end.
Also, the palm fibres that are used for the brushes have quite a strong odour, which further adds to the unpleasantness of using them.
I'll be sticking with using a scrubby cloth and wooden spoon, as it works much better and isn't as messy!