Invisible Writer

Pros
Can be worn on the hand during a long performance without drawing attention to a gimmick.
Hides in plain view.
Comes in lead or grease versions to suit your needs.
Fits extremely well with no fear of falling off.
It can be removed with just a little twitch of your finger.
No fumbling needed to load the gimmick from your pocket.
Instruction video is excellent with many different ideas and presentation styles.
Can be used as a hard hitting mind reading prediction routine.

This is the first writer of any kind I've tried, so I can't compare it to anything. What I can do is tell you if you follow the instructions in the video, you'll be blowing minds! One second it's there, the next second it's in standby, completely invisible.
It took around an hour of practice moving it from one position to another, and another hour to make it a casual movement. The writing actually took less effort than I thought.
Today, I brought it to work with me. One of our customers brought up "mind stuff", so I wrote down a prediction, and laid it under a pen where everyone could see it. Then I proceeded to do a short "Dead or Alive" routine, revealing the name of the dead person he wrote out of a dozen or so alive names. But the sucker-punch got him when I picked up the folded prediction I made, prior to even telling him what I was going to do, revealing, "**** will think of the name Carrol." I thought he might pass out, lol.
My next order will probably include the grease pencil version of this killer, little, gem!

The product is under twenty dollars. I've tried many writers of all shapes and sizes but I have thin long fingers and have not found a writer that I can use with fine control until I came across this one! At the end of the day, there's only so many ways a writer could look like/function. This offers the additional benefit of being able to slip the gimmick off and on with ease. The benefit of having the gimmick 'loaded' at nearly all times is perfect.

However, the instruction video is rather short/barebones (11 minutes) and only covers how to get in and out of the gimmick and how to use the gimmick. For ideas, I would pick up a copy of "The Nail Writer Anthology" by Thomas Baxter. Overall, every mentalist should learn how to use a writer and for me, this is the writer I'll keep. The replacement of lead seems simple enough and I see this writer lasting for a long time.

This is the holy grail of swami gimmicks. Buy it sight unseen.

The invisible writer is a great tool. Unlike other brands of the same type of instrument, this one hides in plain sight from the viewer, it is super comfortable to use (it fits all finger sizes, which is appreciated given that I have very small hands and do not usually I can use this type of devices) and it also achieves super efficient effects. I assume that there will be refills available and if not, in the case of the Pencil Invisible Writer, they are quite easy to replace. There is no con to this great product, basic for mentalists.

This is my favourite writer. The feel is, to me, organic and intuitive. As a beginner it was the first tool that helped me to actually amaze other people, and make me feel that mentalism was an amazing hobby to have.

I got multiple thumb-writers and i have to say, the Invisible Writer is the best. The tutorial to it also well done (how to load the thumb-writer etc...). It is my go to for spontanious mental/prediction tricks (super combo with Memdeck!), there´s no fumbling around, the loading is quick, the writer pretty much undetectable, it´s always in my pocket.

Good quality product and good instructions.
It's a little rich the ad copy. But the instructions are good so it evens out.
The writing is good and the fit is snug. very invisible. But the your skill and how you write and where your eyes are looking is what will be the telling tale if you are going to get called out. It's all about character and how much you can get people to believe you have special skills and are not just doing what you are doing. Theatre and the Thumbwriter.
Sounds like a good title for a book.

Great product. Easy to write with. It does take practice to do the demonstrated put on/take off, but it is a write that should be a part of your kit. Well worth it.

I have tried a number of thumb writers and this one definitely has the best control and is easiest to write with. I can write almost as well as if I had handwritten it for real. My issue is that the lead is very loose. I can only ever be 95% sure that it hasn’t fallen out of the gimmick mid performance. I understand it needs to be removable so people can change the lead when it’s getting down to the end, but I think it is too loose. The grease lead resembles a sharpie very closely, and it would get full marks from me if it weren’t for the looseness of the grip on the lead.