This is a Box Elder Burl. Due to the way burls are formed, the wood grain comes out deformed. Burls are hard to work with, but the beauty they show makes the pain staking process worth it. The style of this pen is a threaded end cap which makes attaching the cap simple and fast. When not in use, be sure to keep the cap on, or the ink will dry out. This pen has no short supply of style, quality, and function. This pen is great for the executive, the pen collector, and the gentleman or gentle-lady with style in your life. The weight of this pen also makes writing large checks (which we do accept) more satisfying.