Social Developmental Toys Vital tools that help foster the mental, physical, emotional and social development of boys and girls. It is fun for children to pound the balls until they drop in the block and slide out. These replacement balls are light enough and measure 1.75 inches in diameter which is just the right size for little kids to grasp hold of. Pack includes The pack 4 different bright colored durable balls. Colors are red, green, blue, and yellow. These balls are not specifically designed for Playkidiz products, it will fit most other Playkidiz products. Safety & Quality Our main concern when manufacturing toy products for little ones. You may be sure that these Playkidiz replacement balls are made of safe durable plastic material. Never worry about what your child is playing with it.