Outer frame dimensions: 36.5 cm x 42.5 cm Inner frame dimensions: 15 cm x 21 cm Thickness: 4 cm No backing board Acrylic cover included Currently, a print is mounted on a styrofoam canvas of the same size. There is no backing board, and it appears to be the type that uses nails to secure the canvas, as there are nail marks. This is common for oil painting canvases, but please secure your canvas by hammering in nails yourself. Thank you for viewing.