SHF (Super High Frequency) Code hopping Digital Transmitter. TX-Transmitter features: Power saving mode, good audio quality, Internal Rechargable Ni-MH batteries, Charging port, Internal Ariel, remote control turn ON from Rx, Size 15l x 4w x 2cm RX- Receiver: 2 channel receiver, channel button, external interchangeble antenna, internal Ni-MH rechargable batteries, Remote Tx turn ON, headphones/recorder Out and volume control. Size:17.5l x 10w x 3.5cm