IGL

I ordered an amped airsoft igl for my polarstar jack 1.1 and the one that came said f2 on the bag and had 1 less row of threads along with a piece of silver metal right below the threads, did they send me the wrong igl or did they update there old design, just in case anyone asks I looked over my order and the paper they sent with the order and I did in fact order a polarstar jack 1.1 igl