Think it belongs to a Chevy, all Stainless, adjustable length 11" to 15", also adjustable tip ~300 deg. ~9/16 dia post.
couldn't find any of the 9ea patent # printed on the arm.
It is an aftermarket "universal arm. The angle adjustment is for the resting position. The curved end blade mount ended in 53 for GM trucks. 54 was the 1st year for curved windshields & the wipers changed accordingly. Fricken wiper may have more info if you need it. wiperman.com
Thank you, very informative..