Neiko Professional Digital Laser Photo Non-Contact Tachometer - Accurate to 99,999 RPM Measurement

I bought this to determine how far off my motorcycle's tach was. It has remarkable pickup of nearly any bright, reflective surface such a chrome or semi-bright aluminum cast so be careful to provide decent background surface isolation. Don't work about running out of reflective tape. I was able to get great results using Testor's silver model paint painted directly on to my engine's flywheel. You can accomplish the same results by painting a spot on a piece of masking tape and sticking the tape to whatever you are reading from.

The down-side of the device is that it is pretty much contoured for hand-held use. I had to rig some velcro to it so that I could strap it to a tripod (leaving me with less to juggle why adjusting carberators). The strapping does make it a little difficult to manipulate the buttons while still being able to see the readout. Don't get me wrong, using this as a hand-held works quite well but does require a steady hand if you are shooting... Read more

The laser tach works as well as you'd expect, measurement range with the reflective tape is 6 feet or more (not sure where Amazon's 500mm description came from, but it's wrong).
The device sends out a beamed laser spot that gets reflected by the tape or any suitably reflective surface. The sensor in the tach picks up the pulses and performs the measurement, displaying in 0.1 RPM steps for speeds up to 999.9 RPM, and 1.0 RPM steps from 1000 to 99999 RPM.

3 AA batteries for economical use with common rechargeables, after the three supplied batteries eventually get used up. They should last quite a while though, using only 40mA during the measurement. The display only comes on when the buttons are actually depressed, so it uses only the minimum amount of battery power- also means it cam't be used for extended unattended measurement however. It has a min and max RPM function, showing the variations in the speed from the measurement.

If you cut a square off... Read more

Bought a number of these for work. They function well. Can't beat the price. Payed $70+ last year for the same unit. The plastic case seems flimsy, so we'll see how they hold up in the field. Also, I don't expect the included vinyl plastic storage/travel case to hold up very well. Otherwise, good product and great price. Will buy more as needed.