4' shingle over ridge vent is a low profile external baffle vent that creates a clean, uncluttered roofline. It installs on the peak of the roof, allowing exhaust ventilation along the entire ridge. An external baffle creates low pressure over the vent openings to pull air from the attic and deflects wind and weather over the vent to help protect the attic from rain and snow infiltration. Venturi Vent Plus has pre-printed slot guides for truss or ridge pole construction and pre-drilled nailing holes designed to assure proper nailing for easy installation. The vent is pre-formed to a 4/12 pitch and fits pitches from 3/12 to 16/12. Provides 18 sq. in. of net free area per linear foot. Built-in ventilating end plug.