Gam3Gear Surecom SF401 Plus Hand-Held Frequency Counter The frequency meter capable of measuring the parameters of the frequency of the continuous carrier signal walkie-talkies , with signal strength indicator. This portable frequency counter is designed for counting continuous wave signal comes from Two-way Radio. There are easy ranges for you to choose. The ranges cover most of the frequency of the two way radios you want to measure. Its four-button control is easy to use and its small size allows you to carry it anywhere you like. Work by TCXO(Temperature Compensate X'tal (crystal) Oscillator) ,In the range of -45 C ~ 65 C can reach  2 ~  4ppm accuracy