Control line planes have always had a flap horn that served as a way to get control from the bellcrank through the flaps to the elevator. If the model didn't have flaps it didn't matter. The horn always had the holes for the clevises in a line. This method uses a bolt through the flap leading edge and two plastic horn brackets facing in opposite directions as yopu can see. I checked travel of the elevator and found it to be the same in up and down. The horn on the elevator points in the opposite direction of the flap horn and cancels out any differential travel.I have yet to try this system in flight as I'm waiting for longer lines to fly with. The model in white is the modified"Fancherized Twister". It's also the one with the new flap horn set up. I was concerned about the c/g but as I added engine and tank the c/g came out just about where it should be. The other is the profile version of Pat Johnston's P-51. This is also waiting for longer lines to come in. The color scheme is from one of the Tuskeegee airmen units of WW2.