Fun Central AY974 1 Piece Light Up Newton's Cradle, Newton Cradle Balance Balls, Scientific LED Ball Cradle EDUCATIONAL ITEM: Excellent educational & science gadget, own your very own piece of scientific history and explore significant values of physics. SIZE: THIS Newtons Cradle Ball measures about 4 x 6 x 7  inches. BATTERIES: 6 AA batteries are required but not included. PACK INCLUDES: Each pack includes one set of this LED Light Up Cradle Ball. MANUFACTURING: This Ball Cradle is environmentally friendly, non-toxic and is designed to last for a long time. Easy to use and absolutely amazing Newtons Cradle Balls.