Fills pretty much the same way as a push filler. The user turns the end knob of the barrel to the right as far as it will go, placing the nib and a bit of the section into the ink well, the knob is then turned to the left while the nib and section remain in the ink. Removing the nib from the ink, the knob is turned to the right to bleed out a couple of drops of ink, turn the pen upright with nib facing skyward and tighten the knob down by turning it to the left again and wipe clean. Pelikan and Montblanc pens tend to utilize this type of filler.  I find it to be the most efficient, easy, and rewarding way to fill the pen, and I tremendously enjoy the ritual of filling the pen these pens.