• High-quality white cardboard, non-fragile and environmentally friendly. • External size: 20.3 x 25.4 cm; internal size: 14.2 x 19.2 cm. • Acid-free and aging-resistant material, with ultraviolet protection. • Three-dimensional effect that enhances the depth and focus of photos. • Protects photos from dust, dirt, and water, preventing direct contact with glass. • Suitable for framing posters, art prints, engravings, lithographs, paintings, and photos. • Ideal for decorating frames in schools, offices, exhibition halls, and galleries.