Dear Hottrockin:
The pen I used was the shorty, although I also own one of the longer ones. The actual pen shown was one of the giveaways for my annual training camp last year. It fits standard pockets very comfortably and, like all their products, is completely bomb-proof. The longer one is a bit harder to carry (polo shirt neckline works best), but provides extra leverage for some techniques.
Either way, you can't go wrong.
Stay safe,
Mike