Plastic Material: The reaction ball is made of plastic, without toxic elements and unpleasant odor, people can play it without too much pressure as it is lightweight and portable UNIVERSAL SIZE: The responsive ball measures approximately 5.5 x 5.5 x 2.8 cm / 2.17 x 2.17 x 1.10 inches, which is suitable for people to hold in one hand Plastic Response Balls: You will receive 4 plastic response balls with randomly colored rope in the bag, good enough for people to play and use; the ropes can be arranged properly when the response balls are not in use FUN GIFT: As a fun tool, the Color Responsive Ball is a great gift for your friends and family who can have a lot of fun with it due to its challenging and fun features Shiny LED Lights: The fun reaction balls are designed with LED lights to make the reaction balls glow brightly when they spin; with this feature, the responsive balls can even be played well at night