Sentence:  Another method of attaching gutters is the spike-and-<WSD>ferrule</WSD> system. Position the gutter, then temporarily nail it to the fascia with 6d common nails at several places. Place the <WSD>ferrule</WSD> inside the gutter at bead height, lined up with the end of a rafter. Drive the spike through the gutter bead, <WSD>ferrule</WSD> and fascia board into the rafter. 
Meaning of the word marked with <WSD> tags:  A metal sleeve placed inside a gutter at the top.