A carbon brush looks like a tiny block of graphite with a wire coming out of one end. Brushes that look identical can still be wrong for your tool by a millimetre on width, by an awkward kink in the lead wire, or by a different terminal at the cable end. Getting the right brush is almost always faster than guessing twice.
Three things confirm the fit. The first is the brush's three dimensions in millimetres: width by thickness by length. Width and thickness are usually within a hair across a brand's range, but the length varies widely and is the single most common reason a “close” brush rubs the holder or fails to seat. The second is the terminal style at the lead end — a slip-on push-fit, a screw-down ring, a spade connector or a soldered lead. Tools from the same brand can use different terminals on different model years. The third is the brush code, if one is stamped on the side of the original. That code is the cleanest possible identifier.
If you have the original brush to hand, measure with a digital caliper and read the code if there is one. If you don't, the next best identifier is the tool's model number from the rating plate. Brand alone is rarely enough — a Makita 9558NB takes a different brush from a Makita BHR240, even though both are popular Makita corded tools.
From there, the routes by brand are: Makita carbon brushes, DeWalt carbon brushes, Bosch carbon brushes, Hitachi and HiKOKI carbon brushes, Hilti carbon brushes, Black & Decker carbon brushes and Titan carbon brushes. For washing machines, dishwashers and similar appliances, see carbon brushes for appliances. The full hub is at carbon brushes for power tools.
If you're unsure, an email with a photo of the old brush and a photo of the tool's rating plate is enough to confirm the fit before you order. We do this several times a day.