This, one time use, rupture disc is designed to activate at a pressure range of 3,600 psi to 4,000 psi. It is marked 4,000 psi. It is recommended for use on DOT spec. 3A, 3AA and 3AL cylinders that have a service pressure of 2,400 psi. For use on TV series valves. *** Discontinued by Manufacturer: Obsolete / No replacements: Purchase of newer valve model recommended ***