Gyro carries a head-scratching machine on his back.
This illustration was included as a poster in a part of the circulation of WDC 355.
The motif seems to have inspired several artists; at least 2 international variants are known to exist, furthermore Barks' sketch was newly inked by William van Horn for the cover of The Carl Barks Library of Gyro Gearloose Comics and Fillers in Color 6 (July 1993).