Silver overlay cocktail shaker, unmarked but probably Czech black amethyst glass with the silver overlay work done in the United States of America most likely by the Rockwell company. The strainer and the red Bakelite stopper are also unmarked. I have heard this referred to as "Tango" pattern glass.
The cocktail shaker depicts two roasters (cocks) in silver overlay that appear to be sizing each other up (for a fight?). This image is repeated twice on the shaker along with a repeating elongated diamond/triangle art deco band around the base that is also done in silver overlay.
The overall height of this cocktail shaker is approximately 15 inches to the top of the Bakelite stopper. This generous sized cocktail shaker is in very good vintage condition. The glass has no chips nor cracks.
Silver Overlay on Black Amethyst Glass Cocktail Shaker with Red Bakelite Finial/Stopper