Empty fields will fallback to default behavior. Note its most likely better to update the title above to be highly clickable.

Google shopping titles can show as little as 20 characters, so best practice is to but the most import parts up front:

Part Number Searches: {Brand} {MPN} {Name} {Modifiers ie material, use case, etc}

Search Names: {Brand} {Name} {Modifiers} {MPN}