Pelikan Level Pens

Is this filling system in a class of its own? Or is it a dropper filled pen where the proprietary bottle serves as the dropper, only able to mate with the Pelikan Level Series pens?

Pelikan developed a novel filling system that they sold from about 1996 to 2006 in two trim levels, Level L5 (colored plastic caps and fill knobs) and L65 (brushed metallic or black trim, and a matching stand). The barrel is the reservoir, and the pen fills from the posting end. The posting end is twisted to allow for filling. A narrow tube on the bottle fits an opening on the posting end of the barrel. Squeeze the bottle to force ink into the pen barrel. When full, detach and turn the end of the pen to seal it. Dots and triangles let you know which position the valve is in. In my mind, this fills a bit like a butane lighter. Reviews I have read indicate that the process is not easy, and ink can leak during the process if you do not hold the pen firmly against the top of the bottle while squeezing the bottle.