terrace doors

This does appear to be a bug flap of some kind. We don't appear to sell this exact style, but believe it or not we sell a shower door sweep that is strikingly similar. Look at our 10-321 and see what you think. The overall length appears to be the same at 1", though the "T" on ours is only 5/32". Yours seems a bit larger, but it is admittedly hard to tell.

Profile diagram of 10-321