Gutter Helmet's patented gutter system only allows water to enter your gutters. Leaves, twigs, and gunk stay out! The secret of our gutter protection system is its textured surface, which makes the rain cling to it as it flows downward. The edge of Gutter Helmet is rounded and extends beyond the gutter. Rainwater curves around the edge and flows into a slit so narrow that debris cannot pass through. Gutter Helmet catches rainwater, and only rainwater! Even though the slit is only 3/8" wide, Gutter Helmet has been proven to handle 22 inches of rain an hour without overflowing—a rate which is more than twice the amount of rain ever recorded in the U.S. Go to GutterHelmet.com for more information.