Someone has gathered quite a few Tails mechanical pencils together. They do resemble the Sonic Pen seen above on this page (were both sorts produced in both a Sonic & Tails version? It's likely) This has the ball shaped top, Segasonic logo, and features the same "Life of Power" quote at the bottom. The Tails stock art is cute and well shaded too. This is a fun mechanical pencil to collect, if you can find it. 

In the gallary you can find a better look at the pen, the Tails themed ball-top pen or possibly mechanical pencil. Of course, there's a Sonic one too, no-matter which this is (pen or pencil) the "Life of Power" quote is there at the bottom, & Segasonic logo at the top.