The picture shows a view of this 1935 N.E.H.D.A. Boston Advertising Celluloid Pin Back Button. It is imprinted in dark blue on a white background. This pinback button is from a group that we are not familiar with. It appears to be a convention badge. There is a paper insert in the back that has a union marking. It is marked on the two sides as follows:
NEHDA MARCH 6 - 7 - 8 1935 MEMBER BOSTON
PILGRIM BADGE & SPECIALY CO. 299 WASHINGTON ST. BOSTON, MASS.
The pin back button measures 1-1/4'' wide. It is in near mint condition as pictured.