When one or two sprinkler heads control or extinguish a small fire, the Sprinkler Stop allows fire crews to stop water damage from occurring without shutting the whole sprinkler system down. This allows the crew to attend to other tasks such as evacuation of the building, ventilation, checking for extension of fire, or starting salvage and overhaul operations -- all without the vulnerability of disabling the entire system. To stop a specific sprinkler simply push rubber stop into the opening of sprinkler head. Turning the threaded handle tightens the gasket and stops the water flow. Easy to carry, easy to use, Sprinkler Stop is a great tool to limit the heartbreak of water damage. You should have several available on each truck. A must for every Fire Department.