* To check the speed of a fast rotating object.
* To check the color drift of printings.
* To check the devices or the products on a production line.
* Baseball : batting training, fielding training, pitching training, or umpiring training
* Tennis
* Golf
* Clay shooting
For example...
An usage example of MJ-01S
When you use MJ-01S for your batting training, stand on the batter's box with MJ-01S on. Then, adjust the frequency and the DUTY ratio until you get the best sight. (The most suitable frequency and DUTY vary between individuals. Try finding the most suitable one for yourself.) You will see the trajectory of the ball or even the stiches on the ball. (Vary between individuals.)
You can also see the difference of the coin rotating with MJ-01S. (slower than without MJ-01S)
You can easily check other fast moving objects as well by following the above.