This listing is for one red and black standard universal typewriter nylon ribbon, which is .5" wide on a spool 2" in diameter. This fits on most typewriters (with the exception of ones with folding carriages). The brand new ribbon comes factory sealed.
If the spool itself happens to not fit, you can always unwind the ribbon from the plastic universal spool and onto the original spool on your typewriter (which I personally like to do especially if the existing spool is original and/or metal!).