Set includes 4 air locks, 4 sturdy white screw-on lids for wide mouth mason jars Use the sturdy, handsome storage case to improve organization in your kitchen. Makes an excellent gift for the fermentation expert in your life. Begin making tasty, healthy sauerkraut, kimchi, ginger carrots, pickles and other fermented foods with safety and ease Silicone gaskets create a tight seal between the lid and the jar, preventing oxygen and dust from contaminating your ferments. size:86mm Material:plastic colour:white Package Contents: 4 x Mason Fermentation Cover Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.