I am a friend of Cast Iron Architecture

I am a friend of Cast Iron Architecture
Title
I am a friend of Cast Iron Architecture
Dimensions 
3.7x2cm (1 7/16 x 3/4 in)
Description 
Robin's Egg blue pin with black lettering reading "I am a friend of CAST IRON ARCHITECTURE"
Credit Line 
unknown lender
Object Number 
Z.3599.3
Due to ongoing research, information about this object is subject to change.
Creative: Tronvig Group