【FOOD GRADE MATERIAL】Our regular mouth canning lids are made of high quality tinplate, the product surface is smooth and not easy to crack, peel or corrode. Food grade mason canning lids are able to be used in the refrigerator, dishwasher and microwave oven. 【UNIVERSAL SIZE】The 70mm diameter of these lids makes them ideal for all regular mouth Mason jars compatible with Ball and Kerr branded jars. 【AIR TIGHT】The inner seal of the lid is made of food-grade environmentally friendly silicone to ensure that the Mason jar lid is well sealed and will not leak. 【ANTI-RUST】Our Mason canning lids are rust-resistant, and you can use these Mason canning lids to replace rusty metal lids and disposable lids with confidence in your kitchen, home and restaurant. 【MARKER LABELLING】We can easily identify the contents of the jar and the storage date by simply writing directly on the surface of the lid with a permanent marker. It can effectively distinguish food products and prevent the use of expired foods.