The Zen rollerball is a very nice pen that comes with a magnetic cap that is also postable on the finial end. Never worry about losing the cap! The body of this pen is made with a very unique piece of Tennessee bog oak. This wood was pulled from a river in Tennessee. The mud in the river turns the wood into a very cool grey and makes the grain look black. The wood could be anywhere from 100s to 1000s of years old. Pen uses any standard rollerball refill.