It’s interesting that the instructions want you to cup your hands around the nipple instead of just spraying yourself directly
I guess they're not as popular now, as trucks have become smarter and more electrified so they don't have to idle as much while still being able to power increasingly efficient devices, plus I guess people just abused the everliving fuck out of them, but it's such an interesting solution to a problem "normal" people wouldn't think about, and one with very visible infrastructure.