What are the tabs for on the GMPP Fuse box?

[stan65]

I am looking to add at least 2 relays one for AC Compressor and the other for a brake vacuum pump. I may add more in the future. I used the extra relay slot in the box to convert from a 1 or 2 fan setup to a series parallel High / Low setup.

Just stole the pic with the metal clip as it showed the black plastic tabs molded on the fuse box.

I could add one of many nice looking relay boxes available, but thought it would me more OEM like if they were on the fuse box.

Thanks for the reply.
Stan