A range of factors influences the selection of which fabrics may be used for what purposes. For example, the selection of fabrics often takes into account the capabilities of particular fibers, dyes, threads and weaves to fulfill specific functions. These functions might be especially utilitarian: thus, a plain, sturdily constructed medium weight cloth is appropriate for durable work clothes. The structures of materials and fabrics, however, need not be the only factors determining selection for a given use. Aesthetic criteria may play a role: some precious cloths, like fine silks, are chosen because by their color and luster, their expense and rarity, they enhance an environment or lend glamour to special situations or events.