The Mendi Headset reads your brain activity in real time and trains the neural pathways behind focus and attention.
https://www.mendi.io/products/mendi
Price: ~300$
Achieve greater focus, clearer thinking and more self-control.
Mendi helps you train your prefrontal cortex with real-time neurofeedback to strengthen focus, overcome stress and help you get more out of life. Just 10 minutes a day for lasting change you can feel.
Frequently used by persons with ADHD as part of their focus-training routine.
The device was used only a handful of time due to health issues completely unrelated to the device.
Payment via TWINT is possible (and preferred)
I sell also another copy of the device, new and with the box still sealed, provided by mistake by the producer.