Bangkok, Siam to USA 1937 cover stamp 15 STG slogan cancel to Ft. Madison, IA

Description

Bangkok, Siam to USA cover stamp 15 STG cancelled, w slogan cancellation 1937 to Sheaffer Pen Co, Iowa
I am going through some of my late grandfather's possessions, and he has some interesting postage stamps and envelopes. Grandpa lived in Ft. Madison, Iowa, where Sheaffer Pen Company was and still is headquartered. At the time, fine pens like theirs were often sold in jewelry stores, so Grandpa has envelopes from lots of jewelers and fancy pen stores around the world that must have once held payments or orders.
This posted envelope was slit at the top with a letter opener to remove contents.
Envelope is hand addressed in ink to the W.A. Sheaffer Pen Company in Fort Madison, Iowa. On reverse is impressed: The Hongkong and Shanghai Banking Corporation, Bangkok, Siam
Normal handling wear. 1 stamps: 15 STG stamp is clear and in nice condition.
Postmarked 10 March 1937 in Bangkok, Siam (now Thailand.) Over the stamp is a slogan cancellation:
"Buy Siamese
Best in the World"
I will ship as soon as I receive payment.