This Rheem 60-101921-81 valve is designed for use in HVAC and refrigeration systems. It features a slow open 2-stage valve and can be used with both HSI and DSI systems. The valve has a diameter of 6.5 inches and a height of 7 inches, making it a compact and efficient choice for a range of applications. With a width of 4.5 inches, it can be easily integrated into existing systems. The Rheem brand is known for its quality and reliability, making this valve a dependable choice for your HVAC and refrigeration needs.