Replacement bulbs > Pygmy and other small bulbs > E10 / MES
Miniature Edison screw (MES, E10) very very small screw bulbs with a roughly 10mm diameter screw thread.
This is also a rare screw thread to find on light bulbs. It's most common uses are in torch bulbs, Christmas decorations, Christmas welcome bridges, Jewish Hanukkah Menorah or German Schwibbogen.