Use 1,With mat, Front opening 4×4 in with mat,Suitable for photos 4×4 in. Use 2, Without mat,Rear opening 5.5×5.5 in without mat. front opening 5.98×5.98 in, Suitable for photos 6×6 in. Size, Suitable for photos 6×6 in without mat, photos 4×4 in with mat, front opening 5.98×5.98 in, overall, 7.2×7.2 in;.