The WIR TX925 is ideal for language interpretation for up to two languages. Operating on 2.3, 2.8, 3.3 and 3.8 MHz, the WIR TX925 is less susceptible to traditional radio and lighting interference. Can operate up to 18,000 sq. ft. in two-channel mode or 28,000 in single channel mode; DOES NOT COME WITH A RECEIVER>Optional WIR RX12-4 four-channel receiver (2 AA batteries, 60 hr. life), WIR RX14-2 two-channel receiver (AAA batteries, 50 hr. life), or the WIR RX16 two-channel/stereo receiver (BAT AP97A NiMH battery pack, 6 hr. life) can be added); MOD 232 Modulator power supply: Wall transformer, 24VAC; 30 minute timer shuts off carrier when no audio is present; WIR TX9 Emitter power supply: Wall transformer, 24VAC; Emitter IR Power: 3.5 watts; 5-year warranty, 90 days on accessories.