Ideal for wet vacuum applications, Liquid Shutoff Assembly limits intake of vacuumed fluids when drum is full, preventing damage to exhaust silencer. Float ball rises as liquid level rises, blocking vacuum inlet to venturi box, ceasing vacuum operation. Wire cage with internal float ball mounts to underside of drum cover and replaces cartridge filter. Mounts using Retaining Springs (N6603) not included. Fits Guardair 55, 30 and 20 Gallon Drum Vacuums and Vacuum Generating Heads. Available as stand-alone item or factory installed option.