Our Backless Acrylic Shadowboxes are the first of their kind, offering UV-protected acrylic to encase your 3-D items, providing exceptional framing grade quality without the time or cost of a custom product. Choose your own backing whether it be wood, canvas, or something else entirely! Hang vertically or horizontally! Includes: Pre-drilled holes. Screws. Lifetime warranty. Clean acrylic with a soft, dry, lint-free cloth, or dish soap and water when needed. Do not use glass cleaners or spirits, which can dull the surface. Our Backless Acrylic Shadowboxes are made to fit over standard-sized canvases. The actual interior dimensions of our shadowboxes are as follows: 16x20" = 16.06 x 20.08" 20x20" = 20.08 x 20.08" 18x24" = 18.03 x 24.06" 24x36" = 24.06 x 36.06" 28x28" = 28.07 x 28.07" 30x40" = 30.16 x 40.16" 36x36" = 36.14 x 36.14" Please make sure your canvas is no larger than the above sizes.