It is made of aluminum. It's a very old wiindow I'd say 1970s or 80s. the tag says the company was from Fostoria Ohio. by your pictures and measurements It looks a lot like it a Swisco window part. I've included an image of the broken pivot lock shoe. it's measurements are appox. 1" wide, 2" tall, 9/16" thick. The only number I can find on the part is a Patent number, 3.055.062. Thank you for your time
