Check the listing for details. Adler Royal 21F Typewriter Ribbons - Adler 21F. Condition: New. Listed at 9.95 USD. ADLER 21F TYPWRITER RIBBONS This Typewriter Ribbon is has a Spool Diameter that is EXACTLY 2 inches and the ribbon is 1/2 in width. We are the Typewriter Experts Description: Nu-Kote B67 Black Nylon Typewriter Ribbon, 1/2 In. X 16 Yards. Limited Quantities Available! We are the Typewriter Experts! This Typewriter Ribbon is designed to work with all of the following Royal Typewriters: Compatible with the following Typewriters: Royal 490 ● Royal 590 ● Royal 591 ● Royal 690 ● Royal 700 ● Royal 770 ● Royal 870 ● Royal 970 ● Royal 972 ● Royal 973 ● Royal 990 ● Royal 991 ● Adler 21F This item normally ships the same business day for orders received by 5 PM EST THE FINE PRINT: This eBay item is a Buy-It-Now item; orders are for a single package of Ribbons. The pictures are of the actual product you will receive. Add a map to your own listings. FREE Trial!