classic silver nickel polish military slider buckle 1.5 width

as advertised ,, this buckle fits my 1.5" wide belt ,, but it's a leather belt which this buckle clamp teeth would not penetrate it ,, so i had to use a razor to slice half the thickness off so the clamp would hold it .. overall ,, this works great as expected .. there is an extra part ,, which i donna know how to use it ,, but did not use it neither for my purpose .. i suspect it is for clamping the end of a web fiber belt before inserting it into the buckle ..