The corner inserts have the number 539 stamped in them.
The thickness is 5/16 of an inch.
The length of the section that goes into the frame is 7/8 of an inch.
The actual sxuare corner is 1 1/8 inches square. The screens are from a Del Mal casement window.
Also, I need two new screens/frames for my casement windows, Do you sell them or can you suggest where I can purchase them. Will my Ace Hardware store be able to help?