..They are the two filler plates which the 'R' model has. When you remove the backrest on the 'GT' you will need them to fill the gaps on the fender as they are not provided with the bike.
I will sell mine as soon as my parts come in to cover the holes left by it.... They've been on backorder since I bought my bike, but I'm only missing one piece of the puzzle now!
My filler plates came yesterday.
I was lucky they didn't cost me anything.
The dealer said because the viewer on the website showed the filler plates in place when I ordered the infill seat cushion that Triumph was shipping them for free (I think they have changed the website now so that when you pick the infill seat it still shows the backrest instead of the filler plates).
It was an easy 15min install.