The "core probe valve" device, or also SYV (Save Your Vacuum), allows to detect the core temperature of the product being cooked sous-vide , creating barrier to the air passage in the point where the needle probe goes through the bag.
The SYV valve can be reused over and over again, i.e. every time the process involves core temperature sensing.
The choice of materials (Teflon, silicone and stainless steel) allows the SYV valve to be used at temperatures above 100°C; therefore the real limit is the type of bag used.