Clips stick to any surface with fingertip pressure. including brick, cinder block, plaster, wood, metal, plastic, etc. They remove with just a twist and can be remounted again & again. Adhesive won't damage walls or materials & never dries out. Better than glue & tape, safer than push-pins, staples & tacks. Great for notes, lists posters, schedules, decorations artwork, projects & much more. 20 clips per pack, bundle of 6 packs, 120 clips total