Definitely a stiff bristle. I used this to clean grout in my kitchen tile. I think it was too stiff to maintain control with my drill. This was more of a product of the stiffness in this bristle which is exactly as advertised.Insanely amazing product! I use this drill brush attachment for my auto detailing business. Specifically, for cleaning floor mats. The mats come out looking new because they do such a good job getting in the small grooves. Way more effective than hand scrubbing.Worked great. Use it for getting insulation off of the interior of an airstream remodel. Did the job in no time. We were amazed by the results. Product is a sturdy and easy to use.I used this Memorial Day weekend to clean up great grandparents old granite headstones. It worked so well! We can now actually read them clearly - magical!This helps so much with cleaning shower tiles. I personally love it.So far it seems to do it all. Won’t know about durability for a while, but everything else seems goodGreat product !It is not sturdy. Doesn't do great job cleaning. Absolutely not strong enough to remove rust. Had to purchase metal brushes to get job done. Would have returned if I'd kept the packaging.La mancha que tenía era muy complicada de quitar, pero el cepillo fue muy eficiente en otras. Creo que aunque no me soluciono todo el problema, no fue por causa del cepillo.Creo que esta muy bien.La verdad, vaya sorpresa me llevé al recoger en paquete, creí que había comprado todo lo que aparece en la foto!Que desilusión al abrir y ver solo un par de cepillos!Meh. Average to mediocre. An old toothbrush is just as effective.Works great. Just as advertisedvienen solo los cepillos