?Upgraded Dual Sensors to Ensure Your Safety?: Compared with most carbon monoxide smoke detectors on the market, our detector sensors have a lifespan of up to 10 years, while other detectors on the market only use three-years life sensors, so our products have a longer service life. The combined smoke and carbon monoxide detector uses a photoelectric smoke sensor and an electrochemical sensor to detect smoke and carbon monoxide faster and more accurately, protecting your home from two potentially deadly threats. ?LCD Digital Displays Multi-directional Sensing Hole?: The informative LCD will show you the battery level and real-time CO levels in PPM (parts per million). If there is fire and carbon monoxide with a concentration over 0.1% db/m, the blue light flashes rapidly. If CO is detected, the red light will flash. Dense gas-sensing holes can prevent alarms from causing false alarms and reduce your worries. ?Battery-Operated Easy Installation?:This CO alarm is powered by large capacity 3x1.5V AA batteries (included), and this combination smoke and carbon monoxide detector can be easily installed using the included mounting bracket, screws, and anchors. The detector's battery life is up to five years, and we also provide a lifetime free battery replacement service to save you money. ?Test Mode Button and Loud Alarm?: It allows you to easily know the working status of the smoke detector and carbon monoxide detector. You can press the test button to inspect the alarm weekly. Alarm Volume: Loud 85dB at 3 meters. The loud 85-decibel alarm is designed to be heard easily. When encountering a non-emergency situation?false alarms occur), you can immediately press the test button and the LED light will flash 10 seconds, indicating that it has entered the silent mode. ?Safety Guarantee and High Quality?: This product has passed the UL standard report issued by the laboratory accredited by ILAC ISO 17025/NRTL standard. We have complete certificates of UL217 and UL2034 testing. Protect yourself and your family from the silent danger of carbon monoxide with our top-of-the-line Carbon Monoxide Detectors. With its advanced detection capabilities, our Carbon Monoxide Detectors offer you an added layer of security and peace of mind. If you have any questions about Yfwsrecinoe smoke and carbon monoxide detectors, please feel free to contact the Yfwsrecinoe team, we will provide you with a Lifetime free after-sales service.