This is a great large grog marker with a very clean wide nib. The marker is intended to be refilled with the brand ink or with any other ink/high flow/pouring acrylic paint.
I wanted this for my artwork, to make bold big marks and thick lines. It works beautifully for that. Also, the nib glides beautifully on all papers I have tried it on.
The marker is cleverly designed. The opening instructions are on the barrel. The screw system is as simple as it gets; I had a bit of trouble opening it, though, due to the plastic being slightly glued on one of the sides, but this was easily fixable. There is an inner cap, with a pump system (a la Posca) to pump the ink/paint out, which also prevents any spilling. It has a small ball inside the barrel to keep the paint/ink liquid and prevent sedimentation. The cap is really safe too.
On the downside, the price is high for an empty small marker.