Since the spiral springs bounce away every time they hit the ground, the kitten stays active! This keeps the young animal entertained for a long time and allows it to expend plenty of energy. The toys come in two sizes and are available in a set of four spirals (two of each size). The spirals are made of plastic. Dimensions: 6 x 2.5 cm and 11 x 1.5 cm (2 pieces each).