It is a linear, semi-crystalline polymer composed of repeating p-phenylene units. The number 6 in the name refers to the fact that there are six carbon atoms in the repeating unit. Nylon 6 is made by ring-opening polymerization of caprolactam. The fibers are tough but retain high tensile strength and elasticity. It is extremely resistant to wear and has low friction with good electrical insulation. In addition, it has excellent chemical resistance. It is ideal for components that move and slide such as bearings, gears, and electronic connectors.