The Danfoss RA-N radiator valves with pre-setting feature are used in two-pipe water based heating systems to ensure optimum distribution of the water in a heating system. Optimal hydronic balancing can provide significant energy savings and improved comfort experience. The pre-setting ring allows precise adjustment of the flow in seven steps - no tools needed. Just give a slight pull and turn the ring with your hand. RA-N valves are available for normal and low flows and for reversed flow.