The Swirl Marshmallow silicone drink bottle belly band (the band with the Swirl logo and pattern) changes colour from pink to purple in direct sunlight, and back to pink when back in the shade. The Swirl Marshmallow drink bottle is made from food grade silicone and is non toxic and BPA free. The bottle is dishwasher safe. The bottles can also be rolled up or folded using the elastic and the bottle can hook onto your bag with the carabiner. The bottles are good quality and well made and do not leak easily. The silicone part of the bottle bottle can withstand drops. The bottle is approximately 700ml. The bottle matches the Swirl marshmallow silicone backpack.