Check the listing for details. 80 METER CW 4 PACK FOR THE OLD BOATANCHOR CW TRANSMITTERS. Condition: Used. Listed at 20.98 USD. YOU ARE PURCHASING ONE LOT OF FOUR 80 METER CRYSTALS IN USED FT-243 STYLE HOLDERS. ONE EACH, 3535, 3550, 3560 AND 3580 KHZ FUNDAMENTAL FREQUENCIES. THESE HAVE THE LARGER, HIGHER POWER VERSION OF THE HC49 CRYSTALS (HC49/U). I SIMPLY REMOVED THE OLD OUT OF BAND MILITARY CRYSTAL ELEMENT AND SOLDERED IN THE HC49/U TALL VERSION OF THIS WELL KNOWN QRP CRYSTAL, WHICH CAN ALSO BE USED IN MANY, IF NOT MOST OF THE OLD BOATANCHOR TUBE CIRCUITS. I'VE USED THESE 49/U TALL CRYSTALS IN MY LITTLE 15 WATT SINGLE TUBE 50CD6 SWEEP TUBE HOMEBREW TRANSMITTER. IT RUNS ABOUT 85 TO 100 MA PLATE CURRENT AND THESE CRYSTALS WORK GREAT, NO ISSUES. THE FREQUENCIES, AS MARKED, ARE APPROXIMATE AND MAY VARY PLUS OR MINUS 1 KHZ, DEPENDING ON CIRCUIT LOADING. SHIPPING TO THE UNITED STATES ONLY.