The SR-400 16 channel receiver features an advanced digital PLL synthesizer to tune all 17 narrow-band frequencies offered in the 72-76 MHz band. Features include a backlit LCD channel display, low battery indicator, and compatibility with the E.D.R. feature in the ST-300 and PST-170 transmitters for improved sound quality. The receiver also includes a special high frequency contour filter and boost switch to increase the intelligibility of the audio signal. Additional features include a battery saving automatic power shutoff when the earphone is unplugged. Batteries and earphones are sold separately.