316 has better corrosion resistance than 304 and is less likely to leach out allergens, making it a material that is less likely to cause allergic reactions. However, both materials contain metals that can cause allergies, so they do not guarantee that allergies will not occur. If you are concerned about allergies, choose 316, and if you have sensitive skin, it is safe to start with short periods of wear. Also, check the type of plating on accessories. Size: 15x12x0.7mm, Hole: 2mm Material: 316 Surgical Stainless Steel Metal Color: Stainless Steel Color Application: Earring Hooks Quantity: 40 pieces (20 pairs) Please note that this product is made overseas and may contain stains, misalignments, minor defects, deformations, and size errors. Please consider this before purchasing (*μ_μ)♪