The use of Spikes & Ferrules is an old method of hanging gutters to a plum fascia. Spikes should nailed through the fascia board and into a rafter tail for proper support and should be spaced 24" - 32" O/C depending on the spacing of the rafter tails. Spikes are driven through the face of the
gutter and the ferrule is a copper sleeve that sits inside the gutter
and acts as a spacer so the nail does not get over driven.