Constructed from food-grade silicone, the Zymatic Keg Seal (KEGSEAL) is perfect for your fermentation process and is weighted for 1 psi of keg pressure. This seal comes with a pre-drilled hole in the middle for foam traps or airlocks. Durable: The KEGSEAL is designed food-grade silicone to ensure that this unit is safe and free of chemicals Pre-Drilled: This keg seal comes equipped with a pre-drilled hole for foam traps or airlocks