The Bionic Worker roller ball pens were designed by Stabilo for demanding professional use. The ink flows smoothly and produces a medium line great for every day writing needs. A small nub on the side of the body prevents the pen from rolling away. The body also features a soft rubber coating and is ergonomically shaped for writing comfort. The high-quality tip is made of nickel silver (a copper alloy with nickel also known as German silver) and gives an extremely smooth writing experience while dispensing the latest Stabilo bionic liquid ink technology.