This bung is made from lead free curing silicone. Suitable for all food and beverage contact. Suited to fit the 5L Demijohns and 23L Carboys. This bung is designed to be used with an Airlock or our EVABarrier 6mm x 9.5mm Hose as a blow off tube for fermentation. Dimensions: 25mm tapered to 38mm Please note the 23L & 5L Demijohn is sold separately.