This is my favorite disposable pen. The size of the barrel is just right. There is a smooth look to it but it has enough friction that it doesn't slip out of my fingers. The five millimeter ball makes writing smooth and there is enough ink flow that a dark smooth line dispenses evenly.With any liquid ink, if the tip is left in one spot too long it will leave a puddle so be careful. On the plus side, the clear window lets you see how much ink is still in the cartridge. Since it is a liquid ink, it moves easily to the bottom of the cartridge when held vertically. I keep them everywhere I have a desk or car and they don't seem to dry out. I haven't had to try to get a stain out of shirt pocket yet so I can't make any claims about that, but I haven't had any problems cleaning it off my skin.One black pen lasts me between three and five months (reds and blues last a lot longer) but I have to keep track of it or people will snag them. I try, but I haven't gotten to completely use all the ink in a single pen yet. :)Buying a dozen at Amazon is the way to go. The local Staples carries (or carried) them only in three packs with one each; black, blue and red, for between four and five dollars. Since I primarily use the black, I was buying two pens that I might never get around to using and that really grates on me. I won't shop at Staples any more because they have changed their rewards program for buying printer ink and severely limit how long you have to use 'reward' coupons. The customer is definitely not always right anymore at Staples. I don't need 'rewards' but, if a store says it's a reward then I should feel rewarded instead of frustrated. If only L.L. Bean carried office supplies! I checked on Monday, but couldn't find this pen in the local Office Max, Office Depot, Target or Costco's. (Sorry about the diatribe!)The Amazon vendor I bought from charged about ten dollars a dozen and that covered shipping! A big improvement for me. If you know what you want and can wait a few days, this is the place to beat. I made the order on Tuesday and got it Saturday. I just hope that Bic keeps making them!I absolutely love these pens! I am super picky when it comes to pens. I work in both the healthcare and the legal professions. Both professions require a lot of writing. Having the right pen makes my work day so much easier! For years I skipped around trying pen after pen, never quite being satisfied until I found the BIC Z4+ Roller, 0.5mm. After I discovered that pen I was set for life, or so I thought. Imagine my horror when I went to reorder them and discovered BIC had discontinued the line (at least the .5mm extra fine point, they still make the .7mm.) After reading tons of reviews and trying a few other pens, I finally came to this one....BIC Triumph Roller .5mm point. OMG! This pen is beyond perfect! As a matter of fact, I love it even more than the Z4+. When I write with this pen it feels so silky smooth. Plus it's sleek and nice looking to boot! I think it's only fair to point out that my husband did complain that these pens, unlike the Z4+, does not have the a comfort grip. He really liked that feature about the Z4. It doesn't bother me, however. I guess the comfort grip just wasn't as important to me as it was to him. Also, these pens are not refillable, but what can you expect for a pen that cost around $1.50? The price here on Amazon is unbelievably low....12 pens for around $10! I found them on the Staples website at $17.99 for a dozen. If you were a fan of the Z4+ .5mm pens, then give this one a try. I don't think you will be disappointed.When the last of my surprisingly awesome extra-fine needle point BIC 730Rs ran out of ink ("surprisingly" because I had always associated BIC with crappy ball-points), I turned to Amazon to replace them, BIC-style. And lo, there were none. After scanning my options, it seemed the 537 was more or less the same as the 730R, which I liked for is decent grip and smooth ink flow.In short, the 537 proved to be a worthy successor and worthy of five stars.The 537 is more or less the same pen as the 730R with some refinements. The body is a tad bulkier than the 730R, but not at the grip. Gone are the raised plastic bevels of the 730R's grip: the new grip has a more textured feel to provide friction. The ink flows nice and clean as before, and the "how much ink is left?" window now takes up most of the pen body's length. The cheap-looking matte silver and gray plastic pf the 730R has been replaced with a more fetching dual-tone silver, almost chrome, effect. The new cap fits better than the old one, and the 537 is about a centimeter shorter in both cap positions. All in all, the 537 is slightly better all-around.The bottom line (since I spent most of the review comparing one pen to another) is that if you're looking for a cheap, extra-fine needle point that puts out a lot of precise black ink in neat little lines, you could do a lot worse than the 537.i am an artist and an ADMITTED pen-aholic. the other side of Hell (at least for me) is filled with ball point pens. everything is made from ball point pens, and the gnashing of teeth is, actually, the sound of ball point pens on a chalkboard.....but, i digress.these pens are PERFECT. the thin, extra fine point, on these pens is a perfect line. not too thick and lays down just the right amount of ink. the MAIN reason any of us are 'pen snobs' is because of the FLOW of the pen. the pen HAS to follow thru with a consistent line and really has to deliver on smoothness. no jumping or skipping of the ink. again, this pen does all that.when i'm sketching or writing or drawing i really do need to have a pen function according to my demand......you will NOT be sorry.i think the irony in my LOVE for this pen is a hoot. i mean, BIC has, always, been known for their hellish ball point pens, and NOW i'm in LOVE with their TRIUMPH ROLLER, EXTRA FINE POINT (0.5 mm)....please, SMILE along with me. ain't life great!!!!