The biggest album of the Nielsen SoundScan era continues to get bigger.

According to Billboard, Metallica’s self-titled 1991 release, which has been dubbed “The Black Album,” this week crossed the 16 million sales threshold.

That gain to 16.002 million, the result of 3,000 weekly sales total, extends the album’s sales record.

It officially became the SoundScan era’s best-selling album in December 2009, when it moved past Shania Twain’s blockbuster “Come On Over.” To date, that album has sold 15.57 million.

The two albums are the only two to move more than 15 million copies since SoundScan tracking began in 1991.