This small-but-innovative pen is more than just a pen. It is three writing instruments in one: a 0.5mm mechanical pencil, a 0.7mm black ink pen, and a 0.7mm red ink pen. Each is housed within the slim 8.4mm diameter shaft and can be changed out with a click of a button. Just turn the pen to the side marked with the writing tool you'd like to use and click! The brass body has a matte finish, with a textured grip for ergonomic use.