Kaliber 44 is a hip hop band formed at the end of 1994 in Katowice, Poland. The group is dubbed the most influential Polish hip hop band, while their so-called Hardcore Psycho Rap style is the most prominent. As revealed by Abradab in an interview aired on TVP, "the name comes from the time we weren't completely sane and played gangsta". Later on members provided a revised interpretation: first part of the name indicates the calibre of problems the group sings about. The number 44 is a reference to a prophetic poem Dziady written by Polish poet Adam Mickiewicz.

"Księga Tajemnicza. Prolog", released in 1996 was the first Polish hardcore psychorap album and the second one where live-scratching technique was used. Their two other albums – "W 63 minuty dookoła świata" (released in 1998) and "3:44" (released in 2000) were completely devoid of psychorap style.