I was part of the crowdfunding for the Kortex device. I was pleased that the voltage is identical to the Fisher Wallace BS. I have only been using it less than one week, so the jury is still out. However, I felt compelled to write this review for the following reasons...
The device looks and feels cheaply made. The power switch, which turns on/off and controls the level of stimulation, is very difficult to use. It's not clear by feeling it whether it's working. If it wasn't for a little 'click' when it goes on or off, I'd be hard-pressed to tell what was happening. The only way I know it's working is if there is a slight visual tremor (not at all uncomfortable).
Finally, since this is a pilot project, one would think I would have been contacted about my feedback. I hope it helps my sleep, but I'm left feeling like they could have tried a little harder given the price.
Bottom Line: No, I would not recommend this to a friend