Pickle Pipes automatically vent CO2 without exposing ferment to mold-causing oxygen. Pickle Pipes can be used to off gas ferments, like pickles, kimchi and more, and vent other fermented foods, like sourdough starters. Dishwasher safe. BPA, phthalate free. Must be secured with a generic Mason jar screw band or Tough Band (not included) Available in packs of 4 for wide and regular mouth Mason jars.