Fuel Injector seal questions

[ElementDO]

I have RC550 injectors and bought a seal kit for my car. The kit is for stock injectors. I was told the kit would work with 550's. My only question is why do I have an extra seal? The one that looks like a micro-machine wheel I have no idea where it goes. Didn't see it in there before....If anything I'm guessing it goes on the bottom. No idea why it has the plastic ridges around it though unless its something for stock injectors? I wouldn't know. This is my first DSM and it came like this.....

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[jcarmichael]

looks like the one that sits inside the actual intake for the injector to go into. I had to go to the junkyard to pull one awhile back because I managed to lose one. I am almost certain thats what it is, I think the ridges are normal if I recall the one I grabbed from the junkyard had them they may wear down a bit over the years though. causing it to be more round like the other two in the picture.

 

[WestCoastDSM]

It looks more to be like the one on the top of the injector. Notice how the edges are the same?