Long setting countdown time: 999 days, 23 hours, 59 minutes, and 59 seconds. Upgraded version with larger size. LCD screen size: 13.8 cm x 4 cm (5.4 x 1.6 in). Alarm sounds for sixty seconds when the set time is reached. Includes clock function with 12-hour and 24-hour format options. Easy to set. Two placement options: magnetic back and adjustable stand. Wide range of applications including vacation, wedding, new baby, retirement, meetings, and study. How to set the clock: Press and hold the CLOCK button until the hour starts flashing. Use UP/START or DOWN to adjust the hour. Press CLOCK again to set minutes and seconds. Press CLOCK once more to confirm. In clock mode, press DOWN to switch between 12-hour and 24-hour formats. How to set countdown time: Press and hold the SET button until a number starts flashing. Continue pressing SET to navigate to the digit you wish to change. Use UP/START or DOWN to adjust the selected number. Press SET repeatedly until the screen stops flashing. Press UP/START to begin or pause the countdown. Press and hold both UP/START and DOWN buttons simultaneously to reset to zero. Powered by 2 x CR2032 batteries (included). Color: Black. Material: ABS. Size: Approximately 15.5 x 5.7 x 1.1 cm. Package Contents: 1 x Digital timer clock. Only the above items are included; other items are not part of the package. Note: Lighting and display differences may cause slight color variations between the product image and the actual item. Measurement error allowed is +/- 1-3 cm.