Battery replacement method: remove it first, slowly pry open from the edge of the bottom cover to replace it, replace the back cover (with a little 502 glue), and then re-attach it with spare 3M glue. As the bottom cover is processed with waterproof glue, it is more difficult to pry.Adjust the time: There is a time calibration hole on the right, you can use a toothpick to adjust the time. If the button is not very sensitive, you can tear the button up, adjust the time and install it again.The B key is invalid: there is a time adjustment key on the right, you can use a flattened toothpick to insert the right key to adjust the time, the up key (A) is the value adjustment key, the down key (C) is the parameter switch key, and the middle key (B ) Is an invalid key.Specification: Type: Mini Motorcycle Digital Clock Material: Plastic Item Color: Black Battery: Built-in AG4 button battery Battery Life: About 1 year Waterproof: IP64 Item Size: 2.7*1cm / 1.1*0.4" (D*H) Package: 1*Clock 2*3M sticker