first of all, sorry for the *hem* attitude. I am glad you took the time to answer me. now, as I said, I have been playing with the mod tools for a while and I usually don't have trouble to do what I want. however, this time, the obvious way of doing it - cloning a hat, removing the "hair top" slot - didn't worked as expected. the hat did not show at first but once I got into a power armor and got out, the hat showed. but, as I should have expected, the wig did not appear and I had a bald character wearing a hat. I tried to remove the "hair top" on the armor addon as well and, the hat never show again. Then, and this is why I asked for a mesh thing, I replaced the hat mesh by the faded visor one. it showed. So, this led me to experiment with some other hats, I tried with the militia hat, the minuteman general hat and hancock's hat. none of them appeared.