This AprilAire 5843Z Humidifier Installation Kit contains all components for step-by-step installation of an AprilAire Whole Home Humidifier with Manual Control, Models 400M, 500M, 600M. Convenient kit saves you time and money over purchasing supplies individually. AprilAire introduced the first evaporative humidifier for forced air furnace systems back in 1954. Since that time, AprilAire continues to lead the industry in whole home humidification systems. Our evaporative humidifiers work by piping water into the distribution tray located at the top of the humidifier. The water is uniformly distributed across the width of the tray and through a scientifically designed system of outlets. It flows by gravity over the Water Panel evaporator. Dry, hot air from the HVAC system moves through the moisture-laden Water Panel evaporator. Natural evaporation takes place, meaning the water is turned to vapor, and the humidified air is circulated throughout your home. WHAT'S IN THE BOX? Model 50 Current Sensing Relay (24V) 10-feet of 18/2 Thermostat Wire (4) Twist-On Wire Nut Connectors 25-feet of 1/4-inch OD Supply Tube 10-feet of 1/2-inch ID Drain Tube 5/8-inch Hose Clamp 6-inch Round Duct Collar 2-feet of 6-inch Round Bypass Flex Duct (4) #8 x 3/4-inch Self-Drilling Screws