Diameter of the badge approximately 27 mm.
Height with suspension approximately 37 mm.
Early "heavy" badges.
Reverse
特別員會章 - Special Member of Association Badge
財團法人 - Foundation
大日本防空協會 - Dainippon Air Defense Association
Hot enamel.
The flower is a separate element of the badge.
Note...
air defense association special member badge
dainippon air defense association badge
japanese air defense association badge
japanese badge
special member badge
大日本防空協会特別会員章
特別会員章