Adam Andrzej Ostrowski, better known as O.S.T.R., is a Polish rapper, musician, audio engineer and record producer, famous for his freestyle rap skills, ambitious lyrics and unique beats. He graduated from the Academy of Music in Łódź, violin class. He is one of the few Polish rappers who have received professional musical education. He has collaborated with American rappers such as Evidence, El Da Sensei, Craig G, Keith Murray, Jeru The Damaja, Lil' Dap, Sadat X and Canadian producer Marco Polo. He has also collaborated with many Polish artists, including jazz musicians Michał Urbaniak, Hades, SOFA, Fokus, DJ Deszczu Strugi, DonGURALesko, Vienio i Pelson, Fu, Pezet, Sistars and Slums Attack. He is a member of bands such as Tabasko, Skill Mega, Killing Skills, Beat Brothers and musical project POE. He is also a former member of Obóz TA and LWC. In 2013, he shared the position of art director of Męskie Granie festival with alternative rock vocalist Kasia Nosowska.

Kendrick Jeru Davis, known as Jeru the Damaja, is an American rapper and record producer. He is known for his 1993 single "Come Clean" from his debut album, The Sun Rises in the East, ranked as one of the 100 greatest hip-hop albums of all time by the editors of About.com. He has worked extensively with Guru and DJ Premier of Gang Starr, whom he has known since he was in high school.