You can adjust the strength according to your own physique, a total of five gears can be adjusted. Low frequency, high frequency two modes to switch at will RELAX BRAIN: This sleep aid can promote neurotransmitters in the cerebral cortex, regulate emotions, thus promoting sleep and helping you relax your brain PHYSICAL THERAPY: The sleep instrument uses physical therapy, and help your brain relax, spontaneously generate sleepiness and enter deep sleep faster PORTABLE: The sleep aid is designed to be portable. Small and portable, it can be used in office, home and business travel, you can use it anytime and anywhere PROMOTES SLEEP: Helps people with sleep deprivation and anxiety fall asleep in just 20 minutes to help you relax more, reduce migraines, reduce anxiety and release stress Material: ABSBuilt in Battery: Lithium ion 500mAH (shipped with built in battery)Gear: 5 gear adjustmentMode: 2 mode