The Pilot V7 Hi-Tecpoint is a refillable rollerball pen, available in a 0.7 size, writing a 0.5mm line, and also a 0.5 size (the V5), and in red, blue, green and red. The black version is properly black, which, sadly, makes a nice change from the grey you so often get.
There’s a nice ink window that lets you see how close you are to needing a new cartridge. The pen is a comfortable size and weight.
The standout feature is the cartridge system. They’re specific to this V7 (and the V5) pen.
The Pilot V7 is great to write with. The nib is smooth (as opposed to the V5, which I found to be a little scratchy, even taking into account that it’s narrower) and lays down a very consistent, though pretty wet, line.
All in all this is a good basic rollerball pen.