The X Pen houses the Pilot Hi Tec C pen refill in a strong and attractive carbon fiber and stainless steel housing. The X-Pen is constructed using a machined carbon fiber tube bonded to a 303 stainless steel tip that accepts the Hi-Tec C cartridge. The stainless steel back is press fit into the tube, and can be easily removed to quickly change out the pen refill. It’s even spring loaded to provide a little “give” if you push hard while writing. The design is simple, smooth, and incredibly strong! This is the type of pen that will outlast you that you can give to future generations.