Brilliant product . Got the old swingball out, and it had a broken string and non-bouncy ball, and I had two miserable children.
But what a great product this is, it comes all set up with the ball on the string, knots in the right places, and a short length of plastic covering the string near the ball to protect it and the loop already to attach it to the post.
It too two seconds to change it over, at the end that attaches to the spiral of the post, there is a loop with a slip knot - so simply slide the plastic cover down, which makes the loop larger, place it over the top of your post, and slide it up again to reduce the size of the loop so it stays on your spiral top. Simple.
Now two happy children, which makes one happy parent!