Our pencil shaped scratch brush has an extra thin, 1/16" diameter fiberglass bundle of fibers that can reach into the tightest of spots. This scratch brush works like a mechanical pencil holder. To expose more brush length, depress the thumb button on the end of the holder, a chuck on the brush end opens letting the bundle of fiberglass fibers slide forward to the desired length. The durable plastic holder measures 5-1/2" in length. The refills for this brush are 1/16" in dia. and 4-1/2" in length.