These mops are the best right now, in my book. They dont leak and there VERY easy to control. Marsh ink and a few drops of dot3 seems to work the best in them, but it will take just about any kind of ink you choose, as long as its thinned out. i have refilled mine 3 times and the nib seems to be holding up just as good as day one. i dont expect it to last forever, but for the price, its completely worth it.