Poster Palooza 21x21 Lacquer Black Wood Shadow Box Square Frame - UV Acrylic, Acid Free Backing, Hanging Hardware Included! This Shadow Box Frame Has Interior Dimensions of 21x21 Inches. Overall dimensions 21.75x21.75 Inches. Moulding Width: 0.75 Inches - Rabbet Depth: 15/16 Inches UV Resistant Frame Grade Acrylic Sheet & Acid Free Backing Included. Hanging Hardware included for vertical or horizontal display.