These are powerful hooks that do a fantastic job holding tight. I use them mostly on the white boards in my classroom, but I have one on a filing cabinet and another on a metal "bin"/office organizer/shelving unit. They are strong enough to hold up the portable speakers that I use for my PPT presentations. I also use them to hold up maps and posters during lessons, to string cords for displays that hold up student work, and to hold my hall pass. I have three in use to hold up a shoe organizer thSee full review