LPG Provida supplies an upgrade kit for the twin cylinder automatic changeover regulator which allows it to regulate four cylinders. The upgrade kit consists of two pigtails complete with tees (highlighted in photo above). To upgrade simply disconnect the standard pigtails, attach the tees to the regulator and then reconnect the standard pigtails to the branch of the tee. The changeover automatically switches to a reserve cylinder when the pressure falls in the active supply cylinder. The indicator arrow turns red when the system has changed over and points to the empty cylinder. The indicator turns white when turned towards the new service cylinder.