http://www.409shop.com/409shop_product.php?id=124303 QUANSHENG TG-K10AT 10KM UHF400-470MHz High quality walkie talkies TG K10AT Two way radio PTT key To make a call, press and hold the “PTT” Key, then speak to the microphone in normal tone. Please keep the microphone 3-4CM away from your lips, to make good communications. Release "PTT" to receive. MON key Long hold to turn on the squelch, release to turn it off. Function (F) key / Exit key. Press “F” key to enter Function interface. Press Exit key to exit A key Full frequency pattern, short hold and frequency goes upwardly, “F+A” in MHz upwardly. Channel Pattern, short hold and channel goes upwardly. Frequency pattern, short hold and channel goes upwardly. B key Full frequency pattern, short hold and frequency goes downwardly, “F+A” in MHz downwardly. Channel Pattern, short hold and channel goes downwardly. Frequency pattern, short hold and channel goes down