Well, that's interesting. I just went out and measured the ball and it's 2.25". I wouldn't go quite so far as to say it looks daft; it did feel a bit big at first, but now i like it. If I didn't have such big hands, I can see how it could be a problem. The original knob seemed a little small to me. The interior is not nearly so dirty as it looks in the photo. Not sure why that is. Something to do with the light.
Lol. Sorry. I can see I was a little blunt there. I only meant it looked daft when I first tried it, compared to the OEM item. Hence I opted for sets of the junior balls too try which are a lot smaller. I still have a few left if anyone wants one. Still only £5 plus post.
Having driven it for a couple of weeks now with the big knob, it seems quite normal now. I think I'll leave it as is. I've still got 15 standard pool balls left, including the cue ball and minus the 8. I don't know what to do with them, they're no good for their original purpose with one missing.