Denier (unit) in the context of "Microfiber"

Microfiber (US) or microfibre (UK) is synthetic fiber finer than one denier or decitex/thread, having a diameter of less than ten micrometers.

The most common types of microfiber are made variously of polyesters; polyamides (e.g., nylon, Kevlar, Nomex); and combinations of polyester, polyamide, and polypropylene. Microfiber is used to make mats, knits, and weaves, for apparel, upholstery, industrial filters, and cleaning products. The shape, size, and combinations of synthetic fibers are chosen for specific characteristics, including softness, toughness, absorption, water repellence, electrostatics, and filtering ability.