Those retractable Sharpies tend to be a little thicker in diameter than the regular Sharpie pens. I haven't seen the ultra fine tipped retractables, but if they are the same size (barrel wise) as the others, the pen itself should be fine. Now, as for the tip itself...depends on what you are having autographed. If you're using an autograph book, I'd say you'd be fine. If it's a baseball cap, t-shirt, or other fabric, I'd go with the thicker tip.