1.Material: 100% Environmental New Material - PP Plastic - No Smell, Harmless to Body.2.Size: Diameter: about 40mm/1.57in, 2.4g/piece Approximately.Colored Ping Pong Balls are light weight and therefore move/roll at the slightest touch , so it is every pet's favorite.3.Teaching Purposes: These colored ping pong balls can be used in multiple classroom games and teaching methodologies ,You can engravethe alphabet, word making, number recognition, counting, patterns, shapes, and much more. The bright colors can let children learn and have fun 4.DIY/Art and Crafts: All ping pongs are perfectly round and have a frosted surface for writing and making; Suitable for beer pong balls parties, decoration, DIY games.They can give a vivid touch to your events like Christmas, Halloween, Thanksgiving, Easter, and Birthday parties.