GRC was established in 1928 and continues to carry common ribbons, as well as ribbons that are obsolete or hard to find. We suggest changing your ribbons after replacing 3 paper tape rolls. These replacement ribbon cartridges are compatible with a variety of POS, calculator, and typewriter products. These are twin-spool replacement ribbons for typewriters. The housing of each ribbon spool measures 2 inches in diameter, the ribbon itself measures 1/2 inch by 24 feet. These universal typewriter ribbons replace manufacturers' parts for Adler, Brother, Olivetti, Olympia, Royal, Sears, Silver Reed, Smith Corona, and Swintec. This item is most popularly used for the Smith Corona models Clipper, Comet, Compact, Silent, and Standard. This product is also interchangeable with the GRC models T5-77BR and the T2-77BR. They produce a rich black and red color and are designed to work with the original equipment manufactured. Use of this product will not void original warranty.