These gel pens should look fairly familiar to you. Their black and blue and red cousins are ubiquitous in US office supply stores. They're great gel pens. Easily my favorite over the even more ubiquitous G2, for their smoother points and better line. I should mention that the clips on this version feel a little flimsy in comparison to the silvery clips on the regular 207. I don't know why exactly. I haven't had one break on me yet, though.
This set is from the BLX line, which offers several colors of ink mixed with black. I've long been a fan of blue-blacks and such in fountain pen inks, and this set of gels comes close to those offerings. (There is also a set of these in the Vision line and the Jetstream line, but I'll have to handle those some other time. These are the best of the bunch, anyway.) Elaine from JetPens says that the green/black version is her favorite. I haven't tried that one yet, but I probably should.
The Brown/Black is probably my favorite, though all of them are good inks, and they all behave the same way. I lent one to a student one period, and I noticed that she had her own the next class.
You can find these pens at JetPens (though I didn't get mine there, I don't think) in several colors. You can also find them in your local stores, I bet, but it's nice to be able to get single pens. There are only a couple of places around here that do that.