Useful Products is a US-based small business established in 2007 by car wash owner, electrician, and former bodybuilder Anthony LaPolla that specializes in drill-cleaning brushes and attachments.
Each of the different brush colors indicates which tasks the brushes are meant for based on their bristle type, so be sure to check which one is best suited for whatever you need to for! Yellow is the “all-purpose” medium bristle, but some are softer and harder depending on what types of surfaces you’re cleaning (but none of them will scratch!).
Promising review: “Among the chores around the house that I do, but do not enjoy, I must say showers/tubs rank right at the top of the list. This kit has been an absolute life-saver. I attach it to a drill and in minutes, my showers and tubs look brand new, scrubbed to a showroom new shine and with a third of the effort required in the past. This cuts my tub/shower/sink cleaning time by about two-thirds, maybe more. I can’t get over how easily this scrubs away soap scum and rust stains. Buy this. Do it now.” —Sarah Ginter
Get it from Amazon for $18.95 (available in six colors).