Attwood Louvered Marine Vent Stainless Steel Attwood hull-mounted vents are designed to install by fastening as a complete unit from either inside or outside the hull. Ventilation hose not included twists into the bottom of the box to form a raised water barrier. All collector boxes and vents are designed for intake or exhaust and meet ABYC H-2 cross sectional area requirements. All-welded 304 stainless steel construction with polished finish. Install with 8 screws. Requires collector box 1487A