They have covers so paint keeps instead of drying out. No need to dump it back and forth, and the size is perfect for children, not to big or too small. You could fill the cups up with about a half inch of paint. The matching color lids and brushes are great for helping kids learn to match. Kids really tried to find a way to make a mess but no matter how often the cups fell, the paint stayed inside. Easy way for kids to access and use the different colors. Makes clean up easier too. Package included: 20pcs Paint Cups with Lids, 10 different color. Paint Cups with Lids for Kids