Retro 51 Smithsonian Collection Rollerball Pen - HummingbirdThis Smithsonian collection pen by Retro51 not only writes with the dreamy rollerball refill, but it also has a hummingbird design acid etched onto the barrel and then plated in stonewashed copper with accents to match. The Smithsonian top ring is engraved with its individual number and then complete with the sun logo on the finial. Each rollerball is packaged in a commemorative tube that will store the pen when it is not in use. The artist, Dr.