Air New Zealand Air Points - Lounge Access in SFO

For those of you who have had the good fortune to fly Business Premier through SFO, which lounge did you have access to (Red Carpet Club or First Class Lounge?) I see the First Class Lounge has showers while the Red Carpet does not. Since Air New Zealand has only two class of service does Business Premier allow access to the First Class lounge to use the shower facilties?

Thanks
Mike

RCC only.