The Camco RV Propane/Gauge Leak Detector is designed to allow you to see at a glance when your propane level is low.Fits a DOT propane cylinder manufactured after 1995 that have the ACME/OPD connection. Type 1 connection for gas grills, RVs and boats Fits a DOT propane cylinder manufactured after 1995 that have the ACME/OPD connection See at a glance when your propane pressure level is low Provides excess flow protection in case of a broken gas line and thermal protection in case of fire Will not read levels immediately: begins working when propane is flowing