Builder Products › Thermoshield Outdoor spa cover package 4x2 1.5lb Image 1 of 1 Thermoshield Outdoor spa cover package 4x2 1.5lb Sale Price: $53.00 Original Price: $63.00 Thermoshield Outdoor Spa Covers 4” x 2” tapered with 1.5lb density foam core and 3mill vapor barrier. Add To Cart Added! Thermoshield Outdoor Spa Covers 4” x 2” tapered with 1.5lb density foam core and 3mill vapor barrier.