Asking for honest feedback for my sales letter

The potential market for this is HUGE... if you present it in the right way. This is essentially a self-improvement product. Self-improvement buyers are RAVENOUS. They're always looking for ways to improve themselves.

By comparison, those who already know and understand what "Entrainment" is and the benefits of it is a very tiny subset of the self-improvement market.

So... I'd lead with the self improvement aspect of it... and in the headline include a hint of intrigue/curiosity alluding to the "HOW".

Something along the lines of this: "Unlock Your Brain's Fullest Potential Using/With/By [Intrigue Statement]"

I don't know what the "intrigue statement" would be without digging into it more. You'd probably use phrases along the lines of "latest discovery", "scientific discovery", "breakthrough", "Brain Science", or get even more specific without using any words the reader doesn't know. I'm sure there is a "hook" somewhere.

You may turn it around, like this: "[Intrigue statement] Reveals The Secret To Unlocking Your Brain's Fullest Potential..."

Then include a subhead that lists some of the benefits.

Your pre-head and headline are Waaaay too long. You should have a short, to the point headline that immediately evokes curiosity.

Again... lead with a general self-improvement appeal with an "intrigue statement" alluding to the how... then explain the "how", the science behind it, the research, the results, etc. in the body of the sales letter.

Make sense?

And this is good illustration of the point I was making. People are
puzzled about how this really works and you can get trapped in
scientific explanations that make the product even more mysterious
(which can sometimes be good for a sales letter) but confused
people don't buy, they leave feeling stupid.

That's why in the sales letter I wrote for this product I explained
the product in every day language and gave examples of how the
reader has already experienced brain wave entrainment.

For example, a common example is if you are driving in the left
lane on a highway at nights, the "on and off" sequence of the
headlights from the vehicles in the opposite lane can cause
you to fall asleep almost hypnotically. This would be a visual
entrainment example.

But you have to use those common experiences to get the reader
understanding what you are talking about.

-Ray Edwards