Taken from Yahoo! Voices
Rain gutter guards are supposed to prevent a homeowner from having to clean out his rain gutters. Made out of aluminum or vinyl, these guards fit over the rain gutter and in theory should prevent solid material from clogging your gutters. Although most rain guards will keep out large debris, guards will not prevent you from having to clean out your rain gutters.
Most people expect they will have to clean out their gutters at least twice a year, once in the fall and once in the spring. Gutters become collection basins for anything that drops on your roof, ranging from leaves, to seed pods, to branches. Over time, these things can pack into the gutter or downspouts, preventing your roof drainage system from working properly.
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