MagVent's Self-Aligning Magnetic Dryer Vent Coupling for New & Existing Construction Involving a 90° Vent Path. The MV-90 is designed for when the vent path takes a 90 degree turn, such as down through the floor, up through the ceiling, or off to the side. The MV-90 can handle offsets up to 3 inches from center to center. Normally, the MV-90 requires 5 1/2 inches of clearance behind the dryer.