- FITS REGULAR MOUTH LIDS: 10 reusable platinum silicone seals. Regular mouth mason jars have a 2 3/8" (60.3 mm) internal diameter. These rings are 70 mm outside diameter, 50 mm inside diameter, and 2.6 mm thick. - SUPERIOR QUALITY: Leak proof, airtight, durable, and designed for better performance than many competing products. Compatible with ball plastic storage caps, stainless steel storage lids, and other lids. Our seals are thicker and include a groove for a secure fit that rises toward the top of the lid. - SAFEST OPTION: BPA and plastic free. Made of platinum cured silicone rubber, these seals are dishwasher, freezer, and microwave safe. Silicone is a safe, food contact material that does not leach chemicals. Platinum cured silicone is purer and more expensive than peroxide cured options. - VERSATILE SILICONE SEAL JAR GASKET: Ideal for fridge and freezer storage, pantry organization, and transporting foods or beverages without leaks. Great for home made fermenting lids and similar uses. For best results, use with threaded closure jars. May not provide an air-tight seal with wire bail or wire clamp closures. Not for canning.