Abstract: When installing vinyl siding on homes or other type buildings, a drawback to the trim pieces around windows, doors, etc., is the method of connecting two (2) retainer strips (J-Channels) together. The original method is to miter the horizontally and vertically placed retainer strips together. This method has proven to be too time consuming and is not neat in appearance. Since then, another way was invented. The new method being a corner piece that must be affixed to the structure having the siding installed. This, too, proved to be time consuming. Our invention is a corner siding piece having an L-shaped base plate with a first leg integral with a second leg, both of which have a first flange and a second flange extending inwardly at the bottom and a curved channel along the top of said first leg and second leg.