The Swirl flamingo drink bottle belly band (the band with the Swirl logo and pattern) changes colour in direct sun from pink to purple, and back to pink in the shade. Swirl Flamingo Drink Bottle is made from food grade silicone that is non toxic. The bottles can be folded or rolled up using the elastic and can hook onto your bag. The bottles do not leak easily and are good quality and are well made. The bottle is approximately 700ml. This is currently the only Swirl drink bottle that changes colour. The bottom colours match the toffee backpack colours.