Rotary knob with one-button operation. So simple that elderly grandmothers and 5-year-old children can use it easily. Silver-colored knob and black body, just twist the knob to set the time, press to start or stop. The digital light will dim after 5 seconds and turn off after another 5 seconds, which can extend battery life. With a magnet on the back, you can attach it to the classroom whiteboard, stove, task, student tablet, iron wall, refrigerator, sports gym, or any other steel surface. Helps students focus on studies, time management in the shower, games, etc., teacher organization for the classroom, moms' cooking, baking, boiling eggs. 3-inch large screen with constant light function. The consistently bright numbers make it easy to read from a distance, even in large meeting rooms, classrooms, or large kitchens and training rooms. 3 levels of alarm sound mode, can be silent, normal, or up to 90db. No unnecessary beeping when setting the timer. You can hear this alarm in another room, so you no longer have to worry about overcooking. A flashing LED digital number will remind you when the time is up in silent mode. Specifications: Material: Electroplated knob + ABS Volume Levels: Silent 0db/Normal 60-70db/High Level 80-90db Voltage: 4.5V Size: Diameter 3 inches * 1 inch Installation: For hanging or standing Operating Temperature: 0-50 degrees Time Range: 0-99 min 55 sec Power Batteries: 3*AAA 1.5V batteries (not included)