The Porelon Universal Twin Spool Compatible Nylon Typewriter Ribbon replaces manufactures parts for Adler, Brother, Olivetti, Olympia, Royal, Sears, Silver Reed, Smith Corona and Swintec. This ribbon provides vivid and consistent black color in addition to exceptional light fastness and durable impressions. This product has been designed and manufactured to operate the original equipment identified, and will not void your equipment warranty. 1 pack. Porelon specializes in creating inking products and elastomers for a wide variety of industries. They focus their scientific, engineering and customer service efforts on delivering solutions that perform to your exact specifications.