Yaesu ATAS-120A 40 Meter through 70cm Auto Tune Motorized HF/VHF/UHF Antenna For FT-857D, FT-450DandFT-897D ATAS-120 For The Following Yaesu Amateur Radio Models - FT-857D, FT-991, FT-991A FT-897D, FT-891, FT-450D, FT-450AT, FT-450, FT-100D, FT-100, FT-857 Only. Covers HF thru UHF, Auto Self-Tuning, motorized Transceiver Mobile Antenna ( 40 Meters through 450Mhz) Designed for mobile (automotive) use, and Requires an Optional Suitable mobile antenna Mount & coaxial Cable. Has PL-259 ( "PO" , "M" ) style base thread. overall length approx 5ft max extended. Motorized "trombone" section Auto lengthens/shortens to tune antenna, when Yaesu radio's tune button is pressed.