Review on 12Pcs Tube Brush Kit - Stainless Steel/Brass Wire Bottle Cleaning, 12In X 6-20Mm - YXQ by Brent Rosecrans

The steel brushes are worth it alone. I use them to clean out carbon on egr ports on a cummins diesel engine all the time. They're also really handy to clean the silicon out of bolt holes on timing covers, oil pans or whatever. The brass is a bit too soft to do the heavy lifting so they're my backups for when I decided to order another set. But overall, worth it.Update: these steel brushes are really hard on aluminum. They’re great for anything else really but be cautious of your base metal.