Foster® 95-50, also known as Foster® Flextra Sealant; is a single component, elastomer based product used as a vapor barrier sealant in the joints of foamglass, PUR, PIR and similar insulation materials, especially in cryogenic insulation applications. It prevents damage to the insulation due to thermal cycles in wide temperature ranges; by remaining soft and flexible at service temperatures between -163 0C and +93 0C.

Foster® 95-50 is mainly used in low temperature (cryogenic) insulation applications to prevent water and water vapor from spreading to the insulation system.