1. [ & Large LED Screen]Just rotate the timer's knob to set the countdown/count up time, and one touch button to start/stop time countdown count up (timing range 00:00 to 99:55). large timer adapts 3-inch LED mirror display, digits are clear at a glance. Both the Seniors and Kids can easily make it work too! 2. [Adjustable Alarm Volume & Silent Mode]The Timer has two levels of volume for you to choose: Loud (80-90dB) is very easy to hear even when you're not around, Soft (60-75dB) is much better when used by to protect their hearing. A Mute level (numbers blink) for study room or library, the visual timer for classroom display will flash to remind you when time arrives and won't bother anyone else. 3. [Two Brightness Modes]Two levels of brightness are respectively "Normal Mode" and " High brightness Mode ", to satisfy your dierent requirements. The display would automatically turn o if there is no operation within 5 seconds, saving your worries that you may forget to turn it o manually. NOTE: It is strongly suggested to set it to "Normal Mode" for extended battery life. 4. [Time Management & Magnetic]Counting down from 99 minutes 55 seconds to zero, or as a stopwatch count up from 0 to 99:55. With two powerful magnets on the back, you can stick to the classroom whiteboard, cooker, student's tablet, iron wall, fridge, sports gym, or other steel places, allows to meet your needs for the most convenient placements in your kitchen, living room, home gym room, classroom, etc.