This is a great little pen. I think it is sold on Amazon by a half dozen or so different companies. My wife got me one a while back and I love it.

I would say 99% of the pens that look like this one take the Parker G2 refill. However, I've found 1 version that takes a Pilot G2 or Energel refill here. Been thinking about picking one of these up to put my favorite refill in, the Energel 0.3 mm Black.