When Rick started thinking about a small tactical pen he wanted to have a pen that is as small as the refill would allow but still have something that you could use to get out of a bad situation if you had too. So as you can, see he kept to the basic idea of all of his pens and kubatons with the deep grooves at each end of the body. This pen also has the same longitudinal grooves in the middle portion of the body as the Extreme Duty pen. So even though this pen is shorter and smaller in diameter you can still get a very good grip on it when striking!
This model like all of his others is also a MODULAR pen. The small bullet on the back of the pen is a separate threaded piece, meaning that they will be adding all of the other attachments such as the warhead, strike bezel, etc.