The first 2 albums may be seminal but quality-wise, 'Master of Reality' is the band's first true classic. Whereas 'Black Sabbath' was a heavy blues album and 'Paranoid' was a psychedelic blues album, 'Master of Reality' is the first real statement from the band that earned their coined 'heavy metal' tag. From the very onset, it's all chugging, down-tuned, fuzzy, big sounding riffs that are synonymous with what heavy metal is today. it is also really their only true heavy metal album, strangely as blues and rock and roll pervades most of their Ozzy catalogue. LP - 180 Gram Vinyl with CD.