These days, cheap removable storage is no problem. USB sticks are virtually free at moderate capacity and not unreasonable, even at relatively large sizes. They are rugged, work across platforms, and don’t require any exotic interfaces. But this hasn’t always been the case. In the 1990s, people wanted to store too much data for floppies, but weren’t willing to shell out for removable hard drives or tapes. Many companies identified this opportunity with, perhaps, the most successful being Iomega with the Zip drive. But there were others, including the Avatar Shark that [This Does Not Compute] remembers in a video you can see below.
Haven’t heard of the Shark? We had not either, but reviewers seemed to like it. The drive would fit in your pocket if you had a fairly large pocket. The 250 MB cartridge was smaller (but thicker) than a 3.5-inch floppy. It performed ok and connected to the parallel port which was common in those days.