Surely anything which can fit into the narrower downpipe and out of the bottom could not clog the underground pipes which are twice the size?

SUPER FLEXIBLE: Made of non-corrosive, weatherproof and waterproof polypropylene, our robust gutter guards will pass the test of time.Before looking more closely at why downpipes need protection its worthwhile clarifying exactly what downpipes are. As noted, our galvanised steel drain pipe covers make it easy to cover and protect existing exterior drain pipes.

VERSATILE – Downpipe guards will fit most common downpipe sizes – very easy to fit – completely flexible.A downpipe gutter is an important component of a building's drainage system that helps prevent rainwater accumulation on the roof. Wall lattices and grids are also sometimes used to enable plants to grow without any adverse load on drainage pipes.