Each brush is designed for a specific use, to clean parts that need heavy duty scrubbing, paint, rust, etc. The bristles are smooth and deep, and gets all the way down into the nooks & crannies in areas that require a narrow face, without breaking. Made of plastic for durability and to resist cracking, warping, and bacteria growth, bent for a secure grip and for knuckle protection. Extra cluster of bristles that helps you reach every corner and crevice, suitable for cleaning tight areas, seams, threads, and soldered joints that require a narrow face. Great set for detailing, shower door tracks, stove tops, tubs, sinks, grout, small engine parts and copper tubing, flaking paint, dirt and scale, surface cleaning, rust, paint & varnish removal.