OEM Subaru positive battery terminal cap/cover. Over time these get chewed up, cracked, or simply lost. Stay safe and keep a neat underhood appearance with a new terminal cover.
There are a couple of different versions of this part. Type A is the narrowest variety, and includes a little "leash" that clips around the battery cable so the cover is less likely to fall off and get lost.
Type B is wider, about 2 1/8" wide at its widest point, and can fit over the fusible link positive terminals that some cars are equipped with.
Fits all 2008-2021 Subaru WRX and STI.