MacBook Pro 13" Retina Display Early 2015 Fan
They are Torx T5 on my MacBook Pro (Retina, 13-inch, Early 2015)
I re-used the ones that I pulled off, and my guess is that they aren’t really necessary since they seem to just fit between the Torx screws and the bottom cover. I really doubt they are part of the heat removal system but are there to prevent vibration.
Use a flashlight and magnifying glass to see how the bottom of the bumper that wraps around the heatsink sits into the fan duct before you remove it. If it is not seated properly it can make noise. You’re welcome.