I treated myself to some ONO products after trying a second-hand full-size steel roller and finding the weight, smooth texture and motion really good, but the size slightly too big for my hands - the Junior roller turned out to be perfect for me. (For context, I have above-average sized hands for an AFAB adult.) I have a substantial collection of different fidget items that serve various purposes, but this has become one of my all-time favourites.
Its silence and sturdiness are excellent - I used it as my go-to fidget throughout my friends' wedding, and it was subtle enough to use even during the ceremony, which helped a lot with the stress and sensory overload of the big day. It's a good size for gripping like a stress ball - there isn't any give, of course, but the solidity is a nice kind of sensory feedback.
The only thing I can think of to potentially improve the ONO steel roller is adding a very small tunnel or pair of holes to the centre of the end piece(s) to allow for attaching it to a sturdy lanyard or wrist strap like a charm or even a watch-style bracelet. This is because it's a bit heavy for putting in pockets of clothes made from lighter fabric - my Popsy dresses in particular can get pulled a bit oddly when I put it in the pockets - so it would be nice to have an alternative carry option for times when you don't want to tote a bag around with you.
Since I was splashing out on shipping/taxes from the US anyhow, I picked up a steel scroller too. I figured it was less likely to suit me personally, but I wanted to give it a try and it's hard to find on the second-hand market in the UK - and I had a friend in mind to offer it to if it wasn't for me.
The scroller is a nice shape and the ball moves very smoothly - I found it a much better experience than the Kaiko Detonator that I picked up second-hand a while back, which has a ball that sticks and scrapes a lot. It was reassuring to have a cleaning tool and lifetime warranty for both products, so I'm not worried about having a similar experience with my ONO fidgets.
I also like that the scroller can be spun on a tabletop - while that does make a quiet sound, it's fun and the hemisphere base is a neat change from standard spinning tops.
I feel like the scroller would probably be most tempting to people who scroll on their phones a lot - that's not a particular habit of mine, so I'm probably not getting the same dopamine hit they would, but I still like it enough to keep it in my collection. In hindsight, I kind of wish I'd picked up one of the keyring holders to go with it so I could try attaching it to a bag.
Overall, I'm really pleased with both products and I feel like it was worth the investment - which is high praise from someone on a low income like me.