DTMF DECODER WHO CONTROLLING 7 RELAYS WITH TONE BACK OUPUT FOR RELAY ON OR OFF. HAVE JUMBER FOR CHANGE WHEN YOU WANT THE SECURITY CODE. HAVE JUMBER FOR CHANGE TO WORK WITH SECURITY CODE OR WITHOUT. HAVE MEMORY ALL RELAY STAGES WHEN THE POWER OFF AND THEN ON HAVE ALL STAGES AGAIN. AUDIO INPUT IS CONNECTED ON TRANSCEIVER,LINKS,RECEIVERS,PHONES,REPEATERS,ETC FOR REMOTE CONTROL.VERY HIGH STABILITY IN HIGH EMI AREAS.IDEAL FOR A LOT APPLICATIONS. FOR MORE DETAIL PLEASE DOWNLOAD:dtmfhelp.pdf