Beginning in 1977, and in response to demand for more durable discs, Wham-O started experimenting with more crack-resistant plastics, resulting in a new line of discs called High Density eXperimental (HDX) Frisbee Discs.
The particular item for sale here is a used HDX 80 Frisbee Disc, in very good condition. It has visible delay marks, as well as some slight marring on the silver hot stamp. It should also be noted that the underside lettering has been removed for cleaner nail delays. This disc has had some low-impact freestyle use. It is vintage plastic from August of 1977, from a production run of only 1,000 (according to the Flying Disc Museum), and hopefully it will make a nice addition to your collection. Thanks for looking!