For use with either Propane or Butane. Quick acting, quarter turn shut-off. Must be placed in the gas line between the regulator and the appliance. Detects both loss of pressure & excess flow. Cuts off gas supply to the appliance automatically and can only be reset manually. A cut-off of this type is mandatory on all British fishing vessels over 10 meters in length using LPG. 3/8" BSP connections.