The Conklin Sherman Company   Push Pull plug has been tested to 60-70 PSI   Molded from all rubber   Nitrile (Buna N)   Very Important - Plugs must be properly installed in a clean dry tube   Plugs must be the right size   Can take temperatures up to 260 degrees Fahrenheit   Push Pull plugs are for a one time use only   Other rubber compounds are available. Please ask us for more information.