Review on FITNATE Tachometer Batteries Reflective Instruction by Russ Charmin

Used unit avoid this seller - Batteries won't fit in unit - Tried different set of batteries - still not working - Manually holding the batteries in place managed to turn unit on - But I I don't want to read the shaft revolutions - I think the single lens design used for the LED and laser is a design flaw - other devices I've seen use two separate lenses.