Reliable alarm designed for the rugged RV environment. Loud 85db alarm alerts you to CO danger. Two-level alarm - low and high. Includes Memory Scan which retains the CO level that activated the alarm. Power 12V AC. Operates at -40-degree to 150-degree F. UL/CSA listed. Surface mount: 5-1/2 in.W x 3 in.H x 1-1/3 in.D. Flush mount: 6-1/2 in.W x 3-1/2 in.H x 1-1/4 in.D. White. One year warranty. UL and CSA listed. 1 per box.