Dezincification-resistant brass Model DZR regulates and measures flow of water in heating, cooling, or water distribution systems to keep them in balance. Unbalanced systems can result in temperature variations that increase energy costs. Flow is measured via pressure tapping points on either side of seat. Threaded-and-solder end Series 1709/1710 has memory stop feature and valve size ID on handwheel and body. Flanged-and-grooved end Series 737 with cast- or ductile-iron bonnet spans 2-12 in.