Plastic screen corners.

I don't believe your corner key is available anymore. The 95-246 might work, with some modification. It has the same 1-1/8" overlap square that you need. You will need to cut out the inside corner to accept the screen cloth when the screen is put together, though. Unfortunately, I can't say with any confidence this will work, as it's just too old, and we've had some customers fail to make this method work. With some corner keys, the screens that used them were in production for only a year before being discontinued, and in those cases the only solution would be to retrofit another corner to fit in the frame, something for which there is no exact science.