Corner for screen with tab for holding it in track

Hello. I'm afraid we couldn't locate this part. It's hard to say from photos but I believe the leg thickness is 3/16 X 3/16". If so, take a look at the 95-064 pair of off-set corner keys and the 95-140 corner key. Both of these types are "self locking" corners that when installed they lock themselves into the window frame. Also take a look at the nylon corner 95-250. This corner has that side pad you have the your corner and internal clips that lock it into the window frame, if that is the type of corner you are trying to replace. I personally think that the 95-140 might be the best fit though I can't make any promises. Review the specifications along with the related videos to see what you think.