Correct, standard rayon batting, on these. Easy to refill, evaporates quickly, smells like naptha, etc, etc.
These work fine for lighting a pipe. As long as you don't badly overfill, and you let them burn for a couple seconds after striking, you're not going to get much, if any, flavour from the naptha. May depend a bit on the fluid you use; Zippo's fluid works great.
I get that a lot of folks prefer butane, but these are wind-resistant. If you smoke a pipe outdoors, it's well worth having one around for times when matches or a butane lighter just aren't cutting it.
The cap on the inner wind-shield is also removable, if you need the fire to go out the top, like a standard Zippo. Just don't try to pop it off while it's hot. And... keep in mind that the giant hole in the side doesn't make them windproof in a vertical orientation.
For what it's worth, you can also send any Zippo in and request a pipe insert; Zippo will send it back with a pipe insert.