Compact Design, easy to hide, difficult to find out Supports 120 hours continuous voice recording or up to 45 days in-car recording ( works 3 hours per day). 8GB internal memory built-in, bigger memory as option  Auto voice activate function support starting recording when in-car conversation starts and stops when the conversation ends. Built-in 2000mAh rechargeable lithium Polymer battery enables device working inside the car around high temperature environment. Industrial-strength magnets built-in supports device being attached under the car seat to avoid regular car cleaning.