Long setting countdown time: 999 days, 23 hours, 59 minutes and 59 seconds. Upgraded version: bigger size. LCD screen size:13.8cmx4cm/5.4x1.6in. It alarm for sixty seconds when arriving at your setting number. With clock function. You can switch between 12 and 24 hours systems. Easy to set. Two ways to place it. With magnet back and movable bracket. Wide application: vocation, wedding, new baby, retirement, meeting, study, and so on. How to set clock: Hold the CLOCK button see the clock number "hour" start flashing. UP/START or DOWN to adjust that particular number. Keep hitting CLOCK to set minutes - seconds. CLOCK again to start. In the CLOCK mode, the DOWN button to switch between 12 and 24 hours systems. How to set countdown time: Hold the SET button see a number start flashing. Push the SET button get to the number you want to change. UP/START or DOWN to adjust that particular number. Hold UP/START or DOWN, the number change quickly. Keep hitting SET until the screen stops