Positive/countdown function: 0.01 second accuracy, with an accuracy of 1 second for timing over 1 hour, and a maximum timing of 99 hours 59 minutes 59 seconds. appearance design: Curved feel, comfortable buttons, sensitive and non lagging. High definition large screen: using acrylic mirror and circular arc design. Shutdown function: saving, press and hold the middle button for 3 seconds to turn on/off. Waterproof for daily use, shock and drop : can prevent splashing water, rainwater, sweat, etc. in ; Adopting ABS anti fall material.