Function: 1. Sealing rings for 15 25, 30 and 60 litre fermenter homebrew, help to maintain fermentation longer. Specification: Condition: 100% Brand New Item Type: Homebrew Air Lock Material: plastic. Approximate weight 80g Size: Height: approx. 120 mm / 4.72 inches. Outer diameter (OD): approx. 34.46 mm / 1.36 inches. Inner diameter (ID): approx. 31.37 mm / 1.24 inches. Package list: 3 x airlock. 3 x sealing ring. Note: 1. Please allow a 0-1 inch error due to manual measurement. Thank you for your understanding. 2. Monitors are calibrated differently, the colour of the item shown in the photos may differ slightly from the actual object. Please take the real one as standard. 3. Have many different qualities for this 3-piece airlock on the market. Ours is made of highly transparent food grade plastic. Almost the same with the photos. 4. Must use homemade tools, please choose our highly transparent food grade plastic tools. 5. Highly transparent means less impurities, but healthier and more hygienic. Features EASY FERMENTING Apply pressure to the airlock when inserting into the drilled plug/plug, and they will last a long time as the transparent airlock is of the highest quality. You can easily see the entire fermentation process. APPLICATION This airlock or fermentation lock is partially filled with liquid (water), sticks on top of a drilled stopper and on top of your fermenter, fits into a grommet lid or drilled bung for beer and wine fermentation. PREMIUM SEALING The Homebrew airlock with sealing rings allows carbon dioxide to escape and prevent the air from polluting your beer or wine, perfect for securing the airlock during fermentation. Durable Material This airlock for fermentation beer vine brewing is made of transparent food grade plastic, environmentally friendly, corrosion resistant and has a long service life. EASY TO CLEAN The beer wine brewing locks are easy to clean. It is a breeze to take these apart and clean thoroughly.