Guitars played by music legends Eric Clapton and Kurt Cobain are going under the hammer in the United States next month with an estimated price tag of up to $2 million each.

Up for grabs at the sale organized by Julien's Auctions in Nashville will be Clapton's Gibson SG -- popularly known as "The Fool" -- which the British rocker began using when his band Cream embarked on its first US tour.

Its custom-painted psychedelic finish makes it one of the most recognizable guitars on the planet, and a key symbol of the "Summer of Love," the 1967 counter-cultural moment that defined a generation.

"The Fool" remained with him for years afterwards, and was key to the development of what was dubbed the "woman tone" -- an oft-imitated sound he produced on the guitar.

Clapton, known for monster riffs in songs like "Layla" and "Sunshine of Your Love," is widely seen as one of the premier guitarists of the last half century.

Also going under the hammer next month is the left-handed Fender Mustang electric guitar played by Nirvana frontman Kurt Cobain on the band's final tour.

The blue Skystang I was one of a number of the models that Cobain bought for the tour, and was the instrument he played at the band's last ever performance in Munich in 1994, the auction house said.

Martin Nolan, executive director of Julien's, said the Skystang I was an important part of pop culture history.

"We all know that Kurt Cobain loved to break guitars and smash guitars, but the Fender Mustang was... his favorite guitar," he told AFP.

"For the last song of his performances, he takes up a cheaper version of the guitar, and that's the guitar that he would smash, but not this baby."

The auction will be held at the Hard Rock Cafe in Nashville from November 16 to 18.

A portion of the proceeds from the sale of the two guitars will go to mental health charity Kicking the Stigma.

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