The Star (XVII) app for iPhone and iPad

Muse 2016 is highly recommended!
Muse 2 can work well when saline fluid is applied to the electrodes, for example Contact Lens Solution by Renu
Muse S has good signal quality but poor coherence measurements

The Star is like a brightness dial for the imagination. It uses advanced neurofeedback to help users develop the focus necessary to overlay the physical senses with any image, sound, sensation, smell or taste they wish. It measures the stability and the complexity of the visualization by measuring the frequency and cross-hemispheric synchronization of brain waves.

Introduction: https://youtu.be/VEMYvJckklE

The Star requires an Interaxon Muse 2016, Muse 2, or Muse S
https://choosemuse.com