Stabilo Bionic Worker Rollerball 0.5mm Medium , Set of 4 , Multicolored HIGH QUALITY The rollerball is the high-quality solution for the exacting professional anytime PROGESSIVE LIQUID-INK TECH It is the perfect tool for any professional who needs flexibility of a liquid-ink pen, ideal for both writing and design PRECISE & SMOOTH WRITING The medium tip with line width 0.3mm, ensures a smooth feeling and aids accurate writing NON-SLIP SURFACE The whole pen shaft has a non-slip surface, making of extended periods of intense work without aching or cramping PREMIUM COLORS High quality rollerball in 4 different pen and ink colors