The demo that landed late musician Prince his first recording contract is up for auction. Boston-based auction house RR Auction is selling Prince’s eponymous demo, which was recorded in 1976, calling it a “stunning revelation for music enthusiasts and Prince fans worldwide.”

At just 18 years old, Prince Rogers Nelson arranged, sang, and played instruments on demo tracks like “Just As Long as We’re Together,” “My Love is Forever” (later featured on his 1978 debut album For You), and the unreleased “Jelly Jam.” Obtained by the estate of late Warner Bros. executive Russ Thyret, RR Auction says that the demo “serves as a testament to the visionary talent of the enigmatic musician and marks the inception of one of the most legendary careers in popular music.”

Enclosed in the custom-made box is a hand-written label with the notice (c) 1977 Prince Nelson, a plexiglass display case, Thyret’s business card, and a CD transfer of the tape’s audio. Accompanying the demo is also a letter of provenance from Jeff Gold, a former Warner Bros. executive who worked closely with Nelson and Thyret.

In other Nelson news, a celebration will be held at the musician’s Paisley Park estate from Thursday, June 8 to Sunday, June 11. Performing during the four-day live event is Nelson’s longtime friend Chaka Khan, Chuck D, and Doug E. Fresh (both of who will also participate in a Hip-Hop 50 conversation), D-Nice, Sounds of Blackness, Stokley of Mint Condition, and more.

The online auction for the demo ends on June 23. The next bid is currently at $12,528.