What are they used for? I thought FP's had a cartridge, do you need a pump to fill them with ink or wash it out? The last time I used a ink pen was in school with an ink bottle in the corner of the desk.
There are two remaining primary methods for inking a fountain pen. The first and most prevalent is the cartridge. Bottled inks must be loaded into a reservoir by way of a pump---generally a piston-pump. In the old days, there were a number of methods to fill the reservoir including by eye dropper.
If you are using Cartridges you don't need the converter at all. If you would like to try bottled ink, place the converter in place of the cartridge, turn the knob on the converter until all the air is out of it, then place the nib in the ink bottle and use the converter to draw ink up. Then you normally use it to force a drop or two out of the pen and you are ready to go. Make sure the ink is for FP's not dip pens.
Does the converter come with the pen kit? If you have the converter do you still need a pump? As you can see I know very little about this. I take it that the converter is the same as a blatter. Thanks