"Great Idea" star star star star_border star_border I think these reusable ice cubes are a great idea. I use them for fizzy drinks and when cooling hard boiled eggs, to stop the water warming up whilst the eggs are cooling and producing a dark ring around the yolk. Unfortunately two of the ice cubes have already leaked, even though I have only used them a handful of times. I checked the packaging and nowhere is there any indication of what liquid (type or quality) is inside the cubes, which are made in China. Jacqueline - 08 March 2021 support_agent A note from the team Thank you for your review. We're sorry to hear this has happened and we've sent you an email. The reusable ice cubes have distilled water in them.