Character:1. It looks fancy and is compact in size2. Very handy to use3. It measures 2, 3 and 4-blade prop rpm4. It shows 4 digits in a 0-32000 rpm range5. It comes with a replaceable 3V 220mAH LITHIUM Battery6. There is an auto shut-off function (no signal detected in 120 seconds) 7. When the LOW BATTERY icon is on, the battery needs to be replaced8. It won't waste any electric power (0£gA) when the TACH is not in use.This may prolong the life of the battery