What is this thing that came with multicutter blade?

Hi,

I recently opened the packaging of a new wood cutting semicircular cutter



for my Dewalt multicutter tool. As I was recycling the packaging, I came across this black piece of metal taped to the card in the packaging.




I have no idea what it is for and the impression I get is that I do not need it. But what is it?

Anyone else come across this?

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