Review on Digital Display Tachometer Inductive Proximity Test, Measure & Inspect by Sam Lund

My boat has all new shielded cables from the engines to the flybridge. I connected the sensor, magnet and wiring as instructed and the readings have never changed from all zeros. I figured that maybe the shielded wiring wasn't good enough, so I connected the display unit directly to the sensor wiring near the motor and got the same result. This product is cheap junk. Don't waste your time.