●Outer measurements - to fit a 8 x 8 inch frame. Exact mount size 201mm x 201mm. ●Inside measurements - to fit a 5 x 5 inch image. Exact aperture size 119mm x 119mm. ●Our mounts and backing boards are cut from conservation grade whitecore mountboard, 1.4mm thick, acid free. Square cut outer edges, bevelled cut on the inner edges. ●This is a pack of 5 sets - 5 mounts, 5 backs, and 5 resealable cellophane bags. ●For other picture sizes and colours please select from the options menus.