This round wire brush features handmade construction. The bristles are oil tempered 22-ga. Steel. The spindle has a .75in loop on one end and .375in pipe threads on the other. Each bristle is individually placed on the spindle in a two-on-placed pattern then positively locked as the spindle is twisted into a double-spiral configuration. These brushes mate perfectly with quick connects that are absolutely essential for efficient cleaning. Measures 7 inches.