Fuel Injector Question
 

I have purchased new fuel injectors from Marren and the original Merc ones that I am replacing have a yellow plastic clip and a steel spring clip on them that the replacements do not have. Can anyone tell me if the clips are necessary and what they do? Are they for displacing heat? (the injector on the left is the new one without the clips, on the right is the old one with clips installed)

Thanks.