The SD (Screw Down) VentSaver mounting plate is for applications where the wood decking is less than one inch or situations where the pipe is off center to the panel flat. This plate works with any VentSaver model and comes with 12 three-inch fasteners that can be screwed into as little as 1/2” of decking below. The plate is 27 inches wide and spans over the high ribs to provide adequate surface area for the VentSaver to be adjusted to compensate for off center pipe placements.