Material: Food grade Tinplate, BPA Free Silicone sealing ring.Diameter: 3.31inch/84mm (For wide mouth jars only).Note: 3.31inch/84mm lids fit 86mm bands, 100% fit for wide mouth jars.Split type jar lids.Rust-proof; Corrosion-resistant; Leak-proof. Thickened material, no bulge or deformation.For one-time use only. Outer edge silicone sealing ring, Our jelly jar lids will create an airtight seal and prevent leakage for hassle-free storage. Made of thickened tinplate, our mason jars airtight lids will not warp or bulge; safe for water bath canning, pressure canning and refrigerator storage.You can easily label or write the date, time and contents information on the big mouth lid with a permanent marker.Tips: Pre-heat the lid before canning. Cool the jar for 12 hours and then test its seal.