They're commonly called penis sleeves or something similar. IMO, they're pretty neat. Any good store that sells sex toys oughtta have 'em. If you shop around, there are some good deals out there.
I wonder if we shouldn't limit the use of "fleshlight" to actual Fleshlight cases, i.e. the popular sex-toy featuring a simulated vagina inside a flashlight-shaped case. In this particular image I would be more inclined to use generic "penis_sleeve"...
Just wondering aloud. I don't usually view futa* so I don't care much one way or the other.