This is a pet bottle holder for keeping drinks cold. It fits 500ml pet bottles. It has a high and effective cooling effect, but since I mainly use a cooler bag and don't use this often, I'm selling two, blue and white, together. I haven't used them much, only a few times, but the white holder has scratches as shown in the photo. There are no problems with its function, but please refrain from purchasing if you are very particular about the condition.