These smooth and comfortable brushes are made of plastic for durability and to resist cracking, warping, soft rubber-grip toothbrush style handle, bent for a secure grip and for knuckle protection. 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. Each brush is designed for a specific use, stiff stainless steel bristles: to clean parts that need heavy duty scrubbing, paint, rust, etc. Crimped brass bristles: to clean unfinished metal parts without damaging surfaces or fine features. Soft nylon bristles: to clean and detailing delicate parts like coffee machines irons. 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.