The ice cube trays are made of PP and silicone material. Each tray makes 6 nice sized ice cubes No forceful bending or twisting of the tray is required. Each tray has a removable lid. This clever tool is very handy for making fully shaped ice cubes while preventing spillage and freezing of excess water and keeping the ice from absorbing freezer odours. In addition, these easy-to-release trays stack easily and neatly in the freezer without a clump. Fill the tray with water, put the lid on and tuck the tray into the freezer. Alternatively, you can fill the ice cube moulds with fruit, ice cream, soda and wine to customise your favourite flavours. A gentle reminder, please don't twist the tray so hard, just gently.