100m Water Resistant Multifunction Men's Black Rubber Strap Digital Luxury Sport Watch GJ-007A High Dependability. Our watches are not dependent on the unreliability of a radio signal to maintain it accuracy. we use built-in artificial intelligence system and Internet calibration capability. Low Power Consumption. CMOS artificial intelligence system requires very little power, our built-in lithium battery can last up to five trouble free years. Low Return Rate. With an 8 year battery life, avoid the frequent product returns experienced by the radio controlled system which often lose accuracy after an average of 18 months. High Accuracy. It is the only watch that can be calibrated over the Internet using GPS timing. And with an accuracy up to one billionth of a second ?High Accuracy. It is the only watch that can be calibrated over the Internet using GPS timing. And with an accuracy up to one billionth of a second.