DIGITAL FREQUENCY COUNTER 6 DIGIT CONTINUOUS READOUT READS TRANSMIT & RECEIVE 8 TO 13.6V DC OPERATION FREQUENCY RANGE FROM 1 MHZ TO 40 MHZ STABILITY +/- 10PPM SIZE 1 3/8" HIGH, 3 1/2" WIDE, 4" DEEP DISPLAY SIZE 3/8" HIGH Blue PLUGABLE ON MOST GALAXY, CONNEX, GENERAL, & SUPERSTAR RADIOS WITH THE 6 PIN JACK ON REAR OF RADIO. WILL ALSO WORK ON MOST OTHER RADIOS BUT MUST BE WIRED INTERNALLY. MOBILE OR BASE OPERATION Very Bright Blue light with Dimmer Button