I installed this onto a new colorbond corrugated steel roof with typical "quad" guttering, where the back of the gutter is lower than the front. It was difficult to install, I had to unscrew the roof sheets so I could predrill holes in the fascia (back of the gutter) for the screws. The stainless screws look pretty but won't stay in the bit holder because they aren't magnetic, so also fiddly. The 125mm version wasn't quite wide enough to fit my gutters so I couldn't sit the front edge on top of the gutter. I got the front edge to fit into the slot in the gutter where the support brackets go, but where there was a bracket I had to cut the aluminium so that the panel would push down into the slot either side of the bracket. If they work well the effort will have been worth it, time will tell.