Please refer to the instructions in the assembly, then everything goes smoothly, it breaks anything from and also the exchange ball goes well over and over again. Cue ball exchange: Does the cat blinks it - a good thing. You pass it flashes - Not good. Batteries tend to empty and then ... you have to completely throw the ball and buy a new one. No Joke. Therefore 2 star deduction. Change buy on eBay, batteries (2 pieces are inside) and stick with something Tesa again or 3 drops of super glue - cut with jigsaw, 50 pieces of batteries by EUR 2: tip from me. So do not ever buy expensive new balls you!