This is the antennae for the MacBook Air. (Antennae hinge cover sold separately)
In this instance, grade-b refers to the fact that some of the very brittle loops along the edge have broken off but the antenna connections are still all in place and is therefore fully functional.
Condition : Grade-B
B-grade means that although fully working and in generally good condition, the product will have minor but noticeable cosmetic marks or defects.
Part Number(s) : 661-5302, 661-4919, 661-5301, 661-4590
Warranty : 3months
Compatibility: