CONTENTS: Pack of 4 automatic venting airlocks for fermenting vegetables.MADE FOR MASON JARS: Fits on the mouth of mason jars to be secured with a screw band (not included). Precise fit for regular mouth mason or canning jars (Bell, Kerr, Bernardin, etc).FOOLPROOF FERMENTATION: These premium quality self burping ferment caps have a one way waterless valve to vent gas automatically while home fermenting vegetables. This simple one-piece airlock requires no water, burping or maintenance.LOW PROFILE DESIGN: Our waterless pipe system is comprised of a low-profile lid that makes storage easier. Our silicone airlocks' valve design takes up less space and allows you to conveniently store your fermenting vegetables in cupboards and drawers.DIMENSIONS: Pickle Pipes measure 2.68" in diameter. Just right for your regular mouth mason and canning jars.FOOD & DISHWASHER SAFE: Made from high grade BPA-free silicone and contains no phthalates. Food and Dishwasher safe.