“B100” is the code for this pentel disposable rollerball pen. However it is now a symbol of rollerball pen in Japan. This pen has been invented for more than 45 years and now still one of the best seller in Japan. Different from regular rollerball pen, the rollerball in the nib of this pen is made of resin instead of metal. Resin rollerball gives it a more flexible stokes as users can adjust the width of the stoke by changing the force applied to the pen. Water-based ink gives it a extraordinary smooth experience during writing. Time flies but the quality resists.