Features: 1 The golf balls with double-layer construction, more rolling far than the singal-layer at the same swing. 2 The interior material is synthetic rubber and the outer material is Sarin, making the golf ball with the characteristics of strong, lightweight and durable, has long life. 4 These golf balls can be practice, novelty golf balls will add to the fun in your game. 5 Bright colors engage young golfers, perfect for any sports fans and can be as a great gift and fun collectible. Specifications: Ball Type:Practice Balls Wind Tunnel:336 Interior material:Synthetic rubber Outer material:Sarin /surlyn Elasticity:Above 75% Diameter:42.6mm Compression hardness:80 Number of hits:More than 1000 times