I've tried a few different types of products in my gutters and these are by far the best. They don't get clogged easily, so you don't need to clean them as frequently, and when you do, they're pretty easy to remove, clean out with a hose & reinstall.

My gutter on sun room is factory made and is a square inside 3 1/2 inch so I ordered the smallest size 3 1/4 inch. They went in perfect with very little space left to fill. There is no brush extending over the inside of gutter, it being 3 1/2 inch deep. I think it will work just fine but hasn't rained yet and leaves haven't fallen, will update later if possible

works as a square deterrent

Installed the brushes in yesterday. Very easy!!

Although I love the product and its simplicity, I would not recommend this product for gutters serving flat or very low pitched roofs. While the gutter did remain unclogged by leaves and other debris, the brushes themselves were completely filled with leaves and pine needles which then became visible from the ground and if left alone, would create issues over time. We opted for a screen mesh style leaf guard which allowed the windy days to clear off any collected leaves.