I'm not sure why. I have not shifted my frequencies a half this way or a half that way. That is what I usedto have to do when hunting in 18khz or the Deus would pick up my pro pointer everytime my propointer would activate. My new Deus, in 18 khz, doesn't make a peep now. It's a pleasing difference. I used to have to shift my frequency a half one way or the other to keep the ProPointer quiet.