Installation is simple and does not require a contractor or special tools. It fits completely inside any 5" K style gutter; the most common style and size on the market today. GutterStuff seals out leaves while allowing large volumes of water to flow through quickly. Made from polyether outdoor durable foam, this lightweight insert won't crumble, dent, bend, or cave in, allowing for satisfied customers. It also prevents mosquitoes from breeding in the gutter. Includes 5 year performance warranty. Patent No. 7208081. Only sold in full carton quantities of 8 each.