Balancing binaural of eight-set frequencies hearing support, Eliminates annoying whistling feedback sound, Surrounding noise elimination, Bluetooth connectivity for mobile, music and video playing, Simple volume control with volume digitalization, Instant DIY hearing test available at Heari Audio App for the real-time hearing conditions, USB Chargeable battery with 10hours battery life after fully charged, The weight of in-ear earplug at 2grams only, The stronger durability with Aramid Fiber of its wires, Waterproof nano-coating cover protection.