Thank you for looking. I am selling my Block 21 SMQV Transmitter so I can switch to Block 19. This receiver is in Excellent condition with no existing problems other than a little wear on the body. This item has served me very well in the past as it will you. Thanks for looking and good luck! DESCRIPTION: Digital Hybrid Wireless™ Technology*  (U.S. Patent #7,225,135) Variable, selectable power output: SMQV: 50mW, 100mW, 250mW Membrane switch control panel with LCD display 256 synthesized UHF frequencies Wide input dynamic range DSP based pilot-tone signal Circulator/Isolator output stage Splash-proof, machined aluminum housing Non-corrosive, super-hard finish he input section features the unique servo bias input circuitry with a standard TA5M type jack for use with electret lavaliere mics, dynamic mics, or line level signals. A DSP-controlled analog audio limiter is employed before the A-D converter. The limiter has a range of more than 30 dB for excellent overload protection and a dual release envelope that makes the limiter acoustically transparent while maintaining low distortion. The limiter recovers quickly from brief transients, with no audible side effects, and also recovers slowly from sustained high levels to keep audio distortion low while preserving short term dynamics. *Digital Hybrid Wireless™ is a revolutionary new design that combines 24-bit digital audio with an analog FM radio link to provide outstanding audio quality and the extended operating range of the best analog wireless systems. The design overcomes channel noise in a dramatically new way, digitally encoding the audio bitstream in the transmitter and decoding it in the receiver, yet sending the encoded information via an analog FM wireless link. This proprietary DSP algorithm eliminates a compandor circuit and its artifacts, and preserves the RF spectral footprint of analog FM designs to simplify multi-channel coordination with exisiting analog wireless systems.