Those are Tenax fasteners. There are German Tenax fasteners and others made in England. They are not compatible. Those are most likely the German ones. The difference is in their size. Here is a previous thread from more than a few years ago. https://www.speedsterowners.co...hat-s-the-full-story
I replaced the snaps on the front of the full tonneau and plan to change all of them eventually. Don't forget if you change the tonneau you have to change the soft top.
They look a lot nicer and they are much more secure than the snaps. Many people opt to use less Tenax fasteners than snaps because they aren't cheap and that is how the originals were done but you'd have to patch the holes in your top and the tonneau if you do.
@Peppy