Hatches are easy to install, and mount vertically or horizontally (invisible fasteners when cover is closed). 180 degrees opening, weather tight seal, reinforced with textured non-skid surface. UV resistant. 1/2" Closed height. ID 14-5/8" x 17" OD 18-1/8" x 20-1/2" Cut Out 15-3/8" x17-3/8" Color White