Papa Het's Hardwired Master Core Signature Strings are available now via Metallica's official web store. The strings will then be available through regular domestic and international retailers starting May 10.
Hetfield and Ernie Ball have been working together for about a decade, trying to design the ideal string set for Hetfield's uncompromising rhythm guitar playing.
"It's only taken 40 years for me to have my own strings," Hetfield joked in a promotional clip for Ernie Ball.
He added that after so many years working with Ernie Ball, the company's heavy core string design was a "major milestone" in their R&D process.
"Heavy? I want heavy," he adds with a laugh. "I'm kind of a barbarian when I play. You've got to have some Metallica calluses to play some of these things at times."
The Hardwired Master Core strings come in a Hetfield-specific gauge set (11, 14, 18, 28, 38, 50) and are said to offer a thick sound with exceptional durability and pitch stability.
Hetfield and Metallica are back on the road this week in South America. The band also has a number of festival gigs lined up in the U.S. this spring and summer, as well as a heap of European tour dates.