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. Sounds alarm for sixty seconds when reaching the set time. Features clock function with switchable 12-hour and 24-hour display formats. Easy to operate. Can be placed in two ways: with magnetic back and adjustable bracket. Suitable for various ocns such as vacation, wedding, retirement, meetings, study, 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 and start. In clock mode, press the DOWN button to switch between 12-hour and 24-hour format. How to set countdown time: Press and hold the SET button until a digit starts flashing. Press SET repeatedly to select the unit to adjust. Use UP/START or DOWN to change the value. Hold UP/START or DOWN for fast adjustment. Continue pressing SET until the display stops flashing. Press UP/START to begin or pause countdown. Press and hold both UP/START and DOWN buttons simultaneously to reset to zero. 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 above items are included; other items not included. Note: Lighting and monitor differences may cause slight color variations between the image and actual item. Measurement error allowed within +/- 1-3 cm.