The lid is made of tinplate. Tinplate material has good thermal expansion and contraction. When used as a sealing material, the container is vacuum waterproof. But when the paint wears off, the cover can easily rust. Replace the cover as soon as it becomes rusted. Excellent sealing: The sealing ring inside the lid of the mason jar makes the can have good sealing performance, which can be used for food preservation. a safe storage. Split Design: Each pack includes 24 split caps, easy for you to replace caps or rings, durable, safe and hygienic. Can lids and can rings are individually replaceable, more economical, to meet your various needs. HIGH QUALITY MATERIAL: Regular mouth mason jar lids are made of tinplate, which can be reused many times, can withstand high and low temperatures, and can be used in refrigerators, microwaves, and dishwashers; our jar rings can be used with most brands of mason jars . MULTI-PURPOSE: Ideal for canned mason jars for airtight storage of spices, candies, cookies, fruits, jams, soft drinks, tea or coffee, nails, screws and other small items. Note: Please confirm the size before purchasing. Material: tinplate Size: 70mm/2.8" Color: silver pack: 24 pieces x mason jar lids 24 pieces x ring split