Pack size: 40 pieces Magnet form: Sphere Diameter: 6 mm Type: Rare-earth Magnet / Permanent Magnet Material: Neodymium Coating: Silver Perfectly sized starting pack for anyone interested of these magnets. You may very well start by buying bigger pack, you will want it eventually any way. But if you have any doubts this 40 spheres pack won't cost you much and gives you an opportunity to start and play. Use for fun, DIY building projects and 3D puzzles.