I have quite a few of these Dubro control horns left over. I'm currently completing a 27% Cap232, 54cc gas conversion. The hardware is expensive, and I don't want to waste them. So I used the Dubros in hardwood on the rudder and elevator. These are THIN control surfaces, just like the Skybolt. I simply sanded off the semi-sphere from one side of the washer thus preventing any pivoting. The ailerons are thick, so there will be no pivoting there anyway.