Slides into the female end of the channels. It also has tabs to fit into the male end of the channels or the cut-to-length end of the channels. The quad allows left or right hand extension of the stormdrain plus or even t and x configurations. The required openings are easily cut out.. Uv inhibited grates are ada and heel guard compliant and have non-slip textured surface. 3 bottom outlets in every channel no clips or screws required to assemble. 4 way corner.