MadgeTech Fitting Gaskets are made specifically for ThermaLock Fittings and Flexible Fittings. For ThermaLock fittings, the tip of the fitting’s probe sheath is inserted through a rubber gasket. For flexible fittings, the threaded end of the fitting is inserted through the gasket. The fitting gasket can be used to provide a seal and cushion for the fitting when it is installed into a test container.