Shingle-over to blend into ridge line. Allows heat/condensation to escape at most effective location. Watertight, passes 110-MPH wind-driven rain test. External baffles help deflect wind/rain, no end caps needed. Prevents roof rot in attic or roof deck. Minimize peeling and extend the life of exterior and interior paint. Limit mold growth. Specially-designed louver spacing helps keep insects out. Energy-efficient, crush-resistant, with internal structural support for added durability. Extra-flexible hinge design for installation on 3:12 to 16:12 sloped roofs. 3" ring shank nails included to insure proper fastening. Edge overhang for smooth, continuous coverage between sections. Provides 18 sq.in/linear foot net-free ventilating area. 40' replaces 18 conventional or ten 12" turbine roof vents. Hip/ridge compatible with traditional sizes (11-1/2 x 12"). "EasyTear" feature allows product to be hand-torn in 3" increments. Boxed.