Delivery State:
External or internal clips? External clips fix to the fascia and show on the face of the gutter, the traditional look. They're sized to the gutter width. Internal clips sit inside the gutter and stay hidden.
Spacing and fall. Clips no more than 1200mm apart. Set the gutter with enough fall to the outlet that water runs off; standing water in a gutter is what starts rust, and ponding isn't covered by the BlueScope warranty.