The Camco 45192 Sunshield Vent Insulator with Reflective Surface has a full 3 inches of foam insulation for insulating your RV roof vent. It fits snugly inside the vent opening for standard 14 inch vents, helping to stop heat transfer and keep your RV cooler in summer and warmer in winter. The reflective surface blocks 100% of the sun's damaging rays.