Rotary Corp brand aftermarket product. Archer Digital Engine Tachometer. Different settings to measure RPM on 2 stroke and 4 stroke engines. Can be used wireless (pulse activation) or wired by using clip on lead provided. Measures RPM from 100 to 19,000 with +/- 10 RPM accuracy level. 0.5 second refrest rate. Similar to PET-1000R & Fits Echo 99051130017.