Smart Vent Model 1540-520 Flood Vent is used where flood protection is required but ventilation is not. Constructed of T316L stainless steel, it is made to withstand harsh marine and chemical environments. The vent door is latched until it comes in contact with standing or slow-moving flood water where it automatically opens to relieve potentially damaging hydrostatic pressure from foundation and enclosure walls. The flood door contains a 2 in. insulated core with an r-value of 8.34, along with a felt strip weather stripping.