This is our innovative design for the Wide Mouth plastic lids that have become so popular. We designed it "in an attempt to overcome the problems inherent to the Mason lid."

They are made of the same material as the plastic Mason lid (polypropylene), but are more durable and more reliable under hot conditions and strong vacuum pressures.

It is approximately 1/8" thick, except where the 'well' is located. The well allows space for the Bubbler. Also, there is no rise along the outer edge of the cap, so spills can run off or be wiped up easily.

The rubber stopper in the center replaces the pressure relief valve and also allows for easy refills of the electrolyzer's water level. There is also a riser around the stopper hole, so contamination won't run back in.