You will find that the black color makes it easier to match with other black connectors and terminals.
Compact Dual Battery Isolator with 140Amp Relay – Ultimate Charging Solution
What stands out about this unbranded relay is that the pin layout is printed right on the top for quick reference.
I noticed the black housing looks clean on the rack and doesn't catch light in distracting ways.
The Omron brand shows up in many shops relay reflects that trusted presence.