on 23 January 2013
I bought this more expensive version of this exec toy as a Christmas present because I wanted it to work well and reviews suggested you get what you pay for. This claims to be identical to the classic original Newton's Cradle. On Christmas Day it worked well, but by Boxing Day it was jangling and tangling. I presume the nylon strings have stretched to slightly different tensions. Looked at from above, one of the balls is out of true, so it will never produce a clean line, no matter how carefully it's set up.
Shame. This was a Christmas present for a small boy who is passionate about science and physics. He's not impressed. If you want one that doesn't work, I suggest you spend less money on it! If you want one that does, maybe don't buy it over the net.