Brush Research GBD41424 FLEX-HONE®, 4-1/4" (108mm) Diameter, 240 Grit, Silicon Carbide, For Mild Steel, Stainless Steel Cast Iron and Softer Ferrous Materials

I recently used the Brush Research GBD40024 FLEX-HONE® (4”) while freshening up the cylinders on a small block Chevy 350, and I’ve got to say—this tool impressed me.Right out of the box, it felt solid and well-made. I chucked it into a cordless drill, added some honing oil, and gave each bore about 5–10 seconds of low-speed rotation. The crosshatch pattern it left was textbook perfect—clean, consistent, and exactly what you want before dropping in new rings.What I really appreciated was how forgiving it is, even if you’re not a pro machinist. It centers itself well and doesn’t gouge or chatter. It’s one of those tools that gives you great results without needing a bunch of setup or precision tooling.One heads-up: it’s not cheap, but the quality and time it saves make it absolutely worth the price. If you’re rebuilding an engine or refreshing an old bore, this hone is a no-brainer.

Really good tool, used on a 6.0 LS block and a 6.2 LT worked perfectly

Used on a 327 that had previously been bored .30 over and just needed a little freshening up.The flex hone and oil did a great job.10/10 recommend

I use these regularly to hone cylinders and they definitely have a great finish and an excellent price point. I buy these in this brand anytime I need a good hone brush.

It's dose It's job perfect

Technique for a ball hone is easily found online but it would have been reassuring to have the instructions directly from manufacturer.It worked as I expected and should last a long time.

Working through my first engine rebuild and wanted to do it right.I would highly suggest reading through several sets of instructions and watching several videos on how to do this. Once you figure it out, it is super simple. Worked well and gave a good cross hatch finish on my cylinders. My only complaint would be one of the balls fell off during use. Other than that still worked fine.

I have to say I love these hones, I had to do an emergency ring replacement on a race engine before an event and there was no way to get the block to the machine shop. I ordered this hone and man it worked great. The finish it left was perfect. I checked cylinder leakage after install but before running and every cylinder was below 10% I had to fire the engine up throw the car in the trailer and make a 1000mile drive to the track. We'll the car ran perfect used no oil needles to say I'm very happy with this hone. Will buy more of these for tricky situations!!!