SWR measures changes in color and strip length:(1).If below SWR_ 2 or SWR_ 3 selected target SWR,the strips are white and green. (2).If the selected target SWR is exceeded, the stripe is white and red. (3).The frequency of the sound varies with the SWR: the smaller the SWR, the lower the pitch. Tone switches sound, mute it off.