Screen corner replacement

Thanks for writing in. Can you tell us the thickness of the screen that these corners are used for? Can you also tell us the thickness of the legs on these corners? From there, we'll do our best to narrow down what you need. 

I believe the corner key you show in your photos is no longer available. It looks like the corners made by Bayforms who were out of Canada. Take a look at the 95-187 corner key for a 5/16" thick screen frame. See if you could use this one as a replacement. If not check with a local hardware store in your area to see if they may still provide these type of screen corner replacements in their inventory.