TTO is the smallest available meter at 50x25x14mm and has large, easy to read digits. Easily mount it to any surface using either the bolt-on (Screws not included) or peel-n-stick mounting options. Features: TTO digital tach/hour meter will work on any gasoline engine This little gauge provides several useful features including a tachometer, a non-resettable hour meter, a resettable hour meter for maintenance, and a clock There is an internal battery so there is no need to connect to power Simply wrap a single wire around your spark plug and mount it wherever you desire