EcoBox Adjustable Picture/Mirror Box (V-9681) Inner box (inside) dimensions are approximately 37" x 3" x 27 1/2". Outer box (inside) dimensions are approximately 37" x 3 1/2" x 30 1/2". Set accommodates items up to 37" x 3" x 61". Full-overlap flaps (FOL) provides extra stacking strength and edge protection. Perfect for artwork, mirrors, tabletops & other flat or narrow products.