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. But the lid are prone to rust when the paint is worn. Please replace the lid as soon as it gets rusty.EXCELLENT SEALING: The sealing ring inside the mason jar lids makes canning to have good sealing performance for food preservation. A safe storage.SPLIT DESIGN: Each package includes 24 pcs of split-type lids, convenient for you to replace the lids or rings featuring long lasting, safe and hygienic. The canning lids and rings can be replaced separately, which is more economical, meet your various needs.HIGH-QUALITY MATERIALS: The regular mouth mason jar lids are made of tinplate, which can be reused many times, can withstand high and low temperatures, can be used in refrigerators, microwave ovens and dishwashers; our jar rings can be used with most brands of mason bottles.MUTIPLE USE: Suitable for sealing the canning mason jars that stored spices, sweets, biscuits, fruits, jams, soft drinks, tea or coffee, nails, screws and other small objects. NOTE: please make sure the size before purchase.Material: TinplateSize: 70 mm / 2.8 inchColor: SilverPackage: 24 Pcs x Mason jar lids 24 Pcs x Rings Split