Featured with max 100 hours countdown and count up, this 6 digit race clock is very cool for outdoor sports events, such as racing & running. Super bright led light display can be easily seen outdoor from 150m away. Internal battery backup maintains marathon time in case of power failure, the clock will start to display accurately as soon as the power is restored. Product details Digit height: 5 inch, 6 inch, 9 inch, 12 inch, 14 inch, etc Digital Color: red, blue, green, yellow, white Functions: stopwatch, marathon timer, count up timer, countdown timer, normal clock, interval timer, FGB, Tabata Timer Display: HH:MM:SS display Double sided: available Material: durable anti-shock aluminum alloy caseï¼? matt acrylic non-glare lens Powered by AC adapter or rechargeable battery or external rechargeable battery, 12V car battery supply Waterproof rating: IP65 Operation IR remote control, RF wireless remote control, start/stop button control, synchronizing master and slave timer control Installation: ceiling/ stand on table/ tripod mounting/car mounting