Metal Lock-in Gutter Guard can be used on 4 in., 5 in. and 6 in. k style gutters. The pre-notched design allows for overlapping which eliminates gaps between the guards. They are easy to install, just slide the flat side under the shingle and lock the curved portion in to the front edge of the gutter. This product is designed to handle high volume water flow and hold up to the heat and cold better than vinyl gutter guards.