because that's not an oil rig, well at least not entirely. I bought it as a general tube (combustion, vape-bong, and oils) and anyway it's on the smaller side, 1 ft, so its not too bad. I definitely agree that you need low filtration for vapor though. I picked up a 18" roor beaker with a single hole downstem off craigslist the other day. after using a pd to vape-bong, the roor tastes absolutely better, despite it being 6 inches taller and having the extra volume of the beaker.