For a better view in the darkness, a built-in light illuminates the watch face from the side. With the Casio A158, you can elapse time, split time and final time measure with 1/100-sec accuracy. The watch can measure times of up to 1 hour. This model is water resistant to DIN 8310 / ISO 22810, and thus is resistant to minor splashing. Any greater water contact should be avoided.