Material: The fermentation airlock is made of high-quality food-safe plastic, reusable and easy to clean. Feature: All fermentation processes are automatic fermentation and exhaust at room temperature, without manual control, easy to use, simple to operate, and can be used repeatedly for a long time. Easy to Use: Just install the silicone stopper/silicone grommets on the appropriate cap, then insert the fermentation airlock, pour water into the airlock, and close the lid. Application: Suitable for wine making, sauerkraut, sealing, fermentation, grape juice, and so on. Delivery Quantity: 4 pcs Package Contents: Only the above package contents, excluding other products. Size: 13 x 5 cm (Reminder: The size is measured manually, please allow 1-2 cm measurement error) Color: White (Due to different monitors and lighting effects, the actual color of the item may be slightly different from the color shown in the picture.)