The lids are made of tinplate. The tinplate material has good thermal expansion and contraction. When used as a sealing material, the container is vacuum-proof and watertight. However, the lid may rust if the paint is worn. Replace the lid promptly if rust appears. EXCELLENT SEALING: The sealing ring inside the mason jar lids provides reliable sealing performance for food preservation and safe storage. SPLIT DESIGN: Each package includes 24 split-type lids, allowing separate replacement of lids or rings. This design is long-lasting, safe, hygienic, and economical, meeting various needs. HIGH-QUALITY MATERIALS: The regular mouth mason jar lids are made of tinplate, reusable, and resistant to high and low temperatures. They are suitable for use in refrigerators, microwave ovens, and dishwashers. The jar rings are compatible with most standard mason jars. MULTIPLE USE: Ideal for sealing mason jars used to store spices, sweets, biscuits, fruits, jams, beverages, tea, coffee, nails, screws, and other small items. NOTE: Please verify the size before purchasing. Material: Tinplate Size: 70 mm / 2.8 inch Color: Silver Package: 24 pcs mason jar lids and 24 pcs rings (sold as split components)