Pens with a writing tip made of a metal ball that is housed in a socket, which allows the ball to rotate freely when pressed against a writing surface, releasing a quick-drying ink. The ball is constantly bathed in ink from a reservoir, one end of which is open and attached to the writing tip. Commercial models of the pen appeared in 1895 and it became popular beginning in the 1930s. It was first patented by Lázló Bíró.
