It's a little (some are 4 inches, some are 6 inches) brush used, I believe, to dab some kind of plumbing compound on pipe connections. But in the sewing room, it's a little miracle worker! The bristles are synthetic and cause just enough static to pick up even the tiniest piece of lint from your sewing machine bobbin area! The thread lint clings to the stiff brush, and you can then just pick off the clump with your fingers. The bristles are stiff enough to get into every nook and cranny, but soft enough not to scratch. The bristles are also firmly attached to the little metal handle, so you don't have to worry about leaving a piece behind.