Only with the correct brush diameter will you achieve the desired success. If it is chosen too large, the brush will push out of the gutter (the stiff bristles cannot conform or wedge in place; they can only give slightly). If the diameter is chosen too small, the brush will sit loosely in the gutter and can be blown out by the wind. Additionally, leaves will continue to accumulate in the gutter. Your gutters and drains will remain free of leaves. With the simple and lightweight insertion of the brushes, you achieve highly effective protection against martens, raccoons, dormice, birds, mice, wasps, etc.