A. From the first introduction of nylon fibers in the manufacturing of carpets, fiber producers have continually improved the quality of the nylon fiber. Each time a major improvement has been made it’s classified as a new generation. We have progressed from the first generation nylon fiber, which was clear and round and actually magnified the effects of wear and soils, to the 5th generation nylon fiber which we are accustomed to today. The 5th generation nylon fiber brought the addition of a "stain resistant" chemical treatment with acid dye blockers that resist most common household and beverage stains. Betco offers a complete line of carpet cleaning products specifically designed to clean stain resistant (5th generation) carpeting.