I just got a beretta px4. It came with the thingamajigger you are describing. I have no friggin clue what it is for. I asked my dealer what it was and he told me, "well its a spacer, of course". and then he laughed, because he had no idea what it was. The only thing I can think of is maybe you could use it to hold parts during dissasembly/assembly. I would love to know the answer to this question.