Yesterday I checked my system from a bank. It really works: if fish tracks are seen in both windows the fish is in center, if in upper window it is on the left, if in lower window it is on the right. Actually I am not very happy with it – in up and down windows it is very hard to compare and see distances to fish tracks, and the windows are also two times sorter in height , it would be much easier to do if windows were side by side (not up and down) like in Lawrence HDI units – they also have up and down splitting plus three more other options of splitting, but Humm DI units just one. I think I will go back to single DI transducer installation: