3 ounce tube of Red RTV Hi-Temp Silicone. This silicone can withstand the high temperatures of an autoclave or pressure cooker. It is self-healing, meaning that it will naturally form an airtight seal after being punctured with a needle. It is often used to make self-healing injection sites in spawn jar lids and to attach 29 mm filter discs
atop of gas exchange holes on custom spawn lids.