For me (smaller hands) this 28.5mm bar is a big improvement over the standard 32mm bar. The only issue, as others have mentioned, is that the knurl on this is too sharp. Rogue's knurl seems to change from one product to the next. Sometimes perfect, and sometimes not. This is a not. You do get used it to very quickly, but the first time you use the knurled version, it won't be fun... FYI you can email Rogue to switch this out if you're ordering a rack and the website doesn't offer the option.

Do you need this? No. But is it the smoothest, most comfortable, and well built Ab Wheel I've used. Yes. The handles alone make it much more enjoyable to use compared to the typical hard plastic handles you find on most models. Not essential, but nice to have.

The 20kg SS OPB is the only "good" bar I've used. Every time I use it, it puts a smile on face. Enough said? As others have commented, the only downside is the thinner competition style collars, which on a Rogue rack can cause some walk out issues. But, if you use sandwich J-cups and some spacer plates while you clean up your walk out, it's all good. Oh, the sleaves are also ribbed, which some may not like. Though I think the latest version has improved this.