This new nylon replacement typewriter ribbon will fit many portable typewriters that have a single pin mounting post with a small drive pin near its base to drive the ribbon. It will fit most portable Smith-Corona, Hermes, Underwood, Royal, Remington, Adler or Sears typewriters. The spool size is 2 inches across and the ribbon measures 1/2 inch in height. See the photos for more detail of this ribbon.