This 3/4 inch gas safety valve is designed to shut off the flow of natural gas to your home in the event of an earthquake. It was developed to save lives and reduce property destruction from earthquake related gas fires. This Little Firefighter(R) valve activates and automatically shuts off the gas supply when triggered by a 5.4 magnitude seismic event. It is approved for horizontal installation on 3/4 inch NPT pipe size for natural gas and propane lines.