What is the name of the part under the iPhone 4 home button?

[iMore Question]

On the middle frame of the Iphone 4 there is a black circle band located where the home button is placed. I am trying to find the name of this part and a place I can purchase it.

 

[Just_Me_D]

If you go to the ifixit website, you will see in-depth instructions w/photos, and therefore, you may find the name of the piece you're referring to. Furthermore, you can purchase the parts from the site.

https://www.ifixit.com/Guide/iPhone+4+Home+Button+Replacement/3144