Mine are the cross laced wire style that go on top of the drip edge and get fastened to the leading edge of the gutter. When I had mine installed, I think the gutter company charged $2/foot to install them but they clean out your gutters before they put them on. Some of the best money I've ever spent on my house!
I also have them on the gutter on the tree house, you can see them in this picture.
