This is a useful mentalism utility device based on an old principle that has stood the test of time.
If you are looking for a hi-tech item, this isn't it. It has the simplest of designs--and requires a
small amount of manual dexterity. But it does the job.
Now, how does this compare to Mental
Pen, which is a similar device? With Mental Pen, you can only have the Sharpie not write and then
write. (The spectator actually does the dirty work of making this happen.) One downside is that the
Mental Pen, while well made, is fragile.
The Write, Not Sharpie, on the other, allows you
to alternate writing and not writing at will. This comes at the small expense of handling and
watching your angles. The the device is quite sturdy. But's more expensive than the Mental Pen.
Both the Mental Pen and Write, Not Right Sharpie get the job done. It all depends what you need.