These empty markers come with different types of tips. There are fine tips (I saw 0.8), chisel tips (of various sizes) and the extra wide block tip.
They are designed for use with acrylic inks. On the label, it says that it can be used with pigmented ink too.
The body is huge and can hold a lot of ink. The large one has a capacity of 20ml. That's like half an ink bottle! The smaller marker has a 5ml capacity, which is also a lot!
The body is translucent so you can easily see the remaining ink. \
The tip is made of hard foam. When there's ink, the ink will soak the form. The whole marker can be dismantled easily for cleaning.
Oh, there's an extra tip provided for each marker.
The feed section uses a spring system. When you press down on the tip, it will open up and let the ink flow through. This is good if you're using ink that does not flow well, such as acrylic inks. If you're using very liquid ink, such as dyed based fountain pen inks, then ink flow is not going to be a problem.
Because the pen can be easily dismantled for cleaning, you can use all sorts of ink. I'm not sure about alcohol inks though, you know those quick drawing ink used in Copic markers? The pen cap is tight but I'm not sure if it's tight enough to prevent alcohol inks from drying.
Here are the strokes from the markers I have.
This ink is Noodler's Lexington Gray.
If you press the tip and let too much ink flow out, you may soak the paper and the ink may go through the paper.
This is Daniel Smith's Walnut Ink.