SIZE4.2*2cm YOU WILL GET A 10 pcs concrete wall hangers kit . There will be no apparent trace left on the wall after removal. And different sizes can meet your different needs. EASY TO USEEach frame hook is composed of four small nails.Just need to gently hammer the four steel nails into the concrete wall until nail end is even with the white plastic hook top. After hanging the frame, the hook is hidden to highlight the art work on the wall. SUITABLE SURFACESThese non-mark hardwall hangers can be applied on many kinds of surfaces, such as drywall, concrete wall, lime wall, whitewashed walls, wood, wooden doors,wallpaper walls., and etc. NOTE: marble wall, glass ,tiles, and stone wall are not suitable. FOR VARIOUS ITEMSThese concrete wall hangers are good helper for hanging home and office art decorations such as clock, photo frame, photo wall, small mirror, clothes, keys, umbrellas, bags, office pendants, etc.