Protmex Digital Tachometer, 50-19999 RPM Contact Tachometer, 100 Groups Data Store Handheld Speed Meter with Backlight, Max/Min/AVG RPM Rotation Speed Gauge, PT6208A (Batteries Included)

Works great, I also purchased the manual operated contact model, which also works very well. Quite handy to have around the shop!

A newly-installed (electronic pulse driven) tachometer proved to be wildly inaccurate. This product allowed me easily to calibrate it. (1) Set the engine to a comfortable RPM above idle. (2) Check actual RPM at the crankshaft pulley. (3) Adjust the tach to match. (4) Repeat to confirm settings.

This unit is fairly accurate, although not intuitive, especially when it comes to determining which wheel is what. The display lets you select between several wheel sizes, one of which does not come with the kit. The power doesn't stay on long, which saves battery, but is a pain because it doesn't hold your mode when it powers itself off. Maybe there's a setting, but I have yet to find it.

Did not work at all. In contact mode no RPM seen by hand. Tried and on machine, no reading. Holding measure button does nothing but lock up the unit requiring the batteries to be pulled to turn off. Instruction sheet horribly wrong. This is pure junk.

Had to read instruction to figure it about after that worked great

The feet / Minute and other modes do not work

I bought this unit after I returned one that was about $10.00 cheaper, but didn't work. This unit gives me very accurate RPM readout when reading spindle RPM on a CNC mill equipped with a spindle encoder and RPM readout. RPM comparison to the CNC mill readouts were within 1% or better. I highly recommend spending the extra $10.00 for this unit.

The 6" wheel that came with the unit is not a true 6 inches. It is approximately 6 1/8 inches. That throws the measurement off approximately 15 to 20FPM when I am attempting to read 600FPM. If I put a true 6inch wheel on the unit it will read correctly. You need to send the correct wheel with the unit.