Air Valve for air duct volume control Material is galvanized, ABS, SUS Size from diameter 2" to 32" Eclectric drive control Electric Valve (damper)For air volume control to air ducting, flexible duct or spiral ductDiameter from 2" to 32" (50mm to 800mm)Material for option: Galvanized Steel, ABS plastic, Stainless SteelActuator by 110V AC, 220V AC, 24V DC, 24V AC Electric Valve