Features 1、Excellent stand by and working time. 2、Prominent sound quality makes it more reliable. 3、Built in 2 mic, can be heard clearly. 4、Automatic monitoring function: as long as it exceeds 45 decibels in 4 meters, it will automatically call back. 5、4 meters, it will automatically call back. 6、Super mini size, easy for carrying. Specification Item Type: Elderly and Child Care Device Compatible Card: GSM, SIM Microphone Range (m) : 5 to 7 radius Reception Sensitivity: about 10K GPRS Operating Temperature: -40 to 50℃ Response Frequency: 1.2K-800Khz Standby Time: 3 to 5 days (without voice control), 10 to 15 days (without voice control) Operating Frequency: 850MHz, 900MHz, 1800MHz, 1900MHz (Please check whether it is compatible with your local system format before purchasing) Battery: 1 3.7V, 300mAh li ion battery Product Size: 35 x 20 x 14 mm /1.4 x 0.8 x 0.6 inches Product Weight: 25 g /0.9 oz Package List 1 x Voice System 1 x USB Cable 1 x User Manual