MASO Digital Tachometer & Timer Gauge - Car Spark Plugs Engine Tach Meter, Motorcycle Electronic RPM Tach with LCD Display for Small Gasoline Engines - Perfect for Vehicle Maintenance & Engine Performance Testing

I have a five star for accuracy but how does anyone know if it’s actually accurate or not? I don’t have a way to calibrate it or compare it to something else. The motor sounded right at the RPM I tuned it to so that’s all I have to really go on.photo shows a wire and clamp. item does not come with wire or clamp and no instructions as to where to attach emI like that it's small enough to carry in your tool box doesn't need batteries and very easy to read ⁰digital R P M readout!!I used it on all my chainsaws when I tuned them up, my pole saw when I tuned it up. Really nice to make sure they running as specked.