Please note: 1.please use at least 12V2A power adapter connect this board,power adapter is very important,make sure your power adapter is in . if you connect with 3T or 4T HDD,please better connect with DC12V3A or 12V5A power adapter. 2.the DVR display resolution is default 1920 x 1080P.If you use a monitor to connect this device, please make sure it can withstand 1920 x 1080P resolution input. or the monitor show black screen after it display first time the Boot logo( show "out of range" or "input not supported") 3.You need to that your monitor resolution can support my device resolution output or support adaptive mode, or you can try to not adapt to the monitor, directly connect to , and then use or APP: xmeye to search for the device and use it. You can also tell us the resolution of your monitor before you make order, and we adjust the resolution output . 4.The device built-in battery, which is used to save and update the time. When there is no power, the time can be saved, but even without this battery, as long as is connected, the time still be updated.for some country,built in battery maybe can not send,So if it returned back due to battery, I hope you can agree send without battery,thank you. 5. Please be careful during operation and take anti-static measures to avoid damage to the circuit. For each product, we test and a video before shipping, confirm that there is no problem before shipping. We are not liable for damages deemed to be caused by improper operation. Color: green Material: PCandmetal What is coaxial Audio: it is mean camera which support coaxial audio connect to DVR which support coaxial too,can No need other device can hear voice from camera by Smartphone or Computer What is Audio over coaxial function 1.it is a nction that the coaxial audio camera connect to coaxial DVR only by BNC cable,then can fer sound and can hear sound from smartphone.No need add sound pick up device