Long countdown setting 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. Sounds an alarm for sixty seconds when the set time is reached. Includes clock function with 12/24-hour format switchable. Easy to set up. Two placement options: magnetic back and adjustable stand. Suitable for various uses such as vacations, weddings, retirement, meetings, studying, and more. How to set the clock: Press and hold the CLOCK button until the hour digits flash. Use the UP/START or DOWN button to adjust the hour. Press CLOCK repeatedly to move to minutes and seconds. Press CLOCK again to confirm. In clock mode, press the DOWN button to switch between 12-hour and 24-hour formats. How to set the countdown timer: Press and hold the SET button until a number starts flashing. Press SET repeatedly to select the digit to adjust. Use UP/START or DOWN to change the value. Hold UP/START or DOWN for faster adjustment. Continue pressing SET until the display stops flashing. Press UP/START to begin or pause the countdown. To reset to zero, press and hold both UP/START and DOWN buttons simultaneously. Requires 2 x CR2032 batteries (included). Color: black/white. Material: ABS. Size: approximately 15.5 x 5.7 x 1.1 cm. Package contents: 1 x Digital timer clock. Only the items listed are included; other items are not part of the package. Note: Lighting and display differences may cause slight color variations between the image and the actual item. Measurement error allowed within +/- 1-3 cm.