Tool in rivet kit?

I'm getting ready to assemble my first 1919, I'm scared S**tless, but I'm very carefully going over all the build tuturials and I'm almost ready to start,I was going through my rivet sets making sure I had enough of each and sorting them into little snack baggies,I came across this in with all my rivet bags, I always assumed it was a rivet till I actually read the bag, this kit was purchase from Sarco about 10 years ago before resonable semi side plates and internal were available, so I'm not real surprised there is some thing wrong, or at least extra with the kit, they also shorted me a front sight which I didn't realize till now, but I guess this "tool" and the extra rivets is their way of making up the difference. I looked through my TM and didn't see this listed there. Thanks Bob.