Inorris,
The white horns for the tail screw into each other, one top and bottom, the aileron horns have #2 screws that should fit. Mine came with #3s and you can't use them with the metal horns w/o drilling them. I called Dave Patrick and spoke to him and it appears that they cahnged out the horns from CF to metal but forgot to put the new screws in. I got the #2s and they seem small but I pre-drilled them and then used some CA to secure the threads and they seem very strong.
Jeff