Check the listing for details. BurpLids® 4 Pack Curing Kit - Includes 4 Lids & Extraction Pump. Color: Black, Condition: New. Listed at 31.95 USD. BurpLids® 4 Pack Curing Kit - Fits All Wide Mouth Mason Jar Containers - Home Harvesting Essentials Includes 4 Lids with Extraction Pump - Vacuum Sealed for successful CureBurping Made Easy - No more frustrating time consuming untwisting and prying off lids. Use the oxygen extractor pump to burp the jar. Simply place, pump, press, done!Airlock Valve Technology - Burp Lids use waterless airlock valve technology which functions as a sealing vapor lock for your container, allowing carbon dioxide to escape without letting oxygen in.Date Tracker - Keep track of batches with our date tracker embedded in every lid! No more needing to remember when that batch started.Minimizes Chances of Rot - These lids create a vacuum seal inside your jar. It is very hard for contaminates to grow in a vacuum increasing your chances for success!BurpLids® are Curing Lids that will make your Curing experience a whole lot easier, stress-free and successful. You have every good reason to try the Curing Kit Lids for wide mouth mason jars today!