The EDK is a compact, machined rollerball pen that comes with one of the best ink cartridges on the market today (Schmidt P8126) and will accept any Parker ballpoint compatible refill. Each pen is a little over 5.0" long and .435" in diameter (minus the clip). The all aluminum pen weighs 1.0 oz, the aluminum and brass/copper versions weigh 1.6 oz, and the all copper or brass versions weigh 2.1 oz. The bodies of the EDK are machined from 6061 Aluminum, C360 Brass, or Tellurium Copper and will feature a tumbled, or tumbled then anodized finish to help hide any potential damage and give it extra grip. The brass and copper pieces come in a raw tumbled finish and will develop a beautiful aged finish with time and use. By mixing and matching materials, you can customize the balance and feel of the pen. If you like a front heavy pen, choose an aluminum upper section and copper or brass lower barrel section, for example. The area in the grooves and knurling maintain a different finish and will provide visual interest as the pen ages. We are using the same bulletproof stainless steel clip and screws as we do on our other pens so you don't have to worry about breaking your clip like you do with most other pens. The German all-metal "click" mechanism is virtually silent and provides a smooth action to the pen. Our pens are designed and manufactured, by us, here in the USA. The click mechanism on the EDK is a precision mechanical assembly designed and manufactured by Schmidt, in Germany. Aggressive clicking or “flicking” of the mechanism can cause damage to the internal workings of the assembly resulting in poor performance. This is usually indicated by a gritty feeling or by irregular functionality. This type of damage is not considered normal wear and tear and will not be warrantied as being defective. Replacement parts are available, but at a cost to the customer.