40dB of hearing enhancement; 1 environmental adaptive listening mode; 4 digital sound processing channels; 20-bit audio processor for crisp, clear sound; 8-band graphic equalizer; Nano-tech water repellent coating; Automatic feedback control; 20% smaller than Game Ear Series 1 ; Toggle volume control; Sound activated compression (SAC); Low battery tone indicator; NR:R 29dB; Requires #13 battery;