This is the shocking moment a prison inmate smashed a 'sock filled with pool balls' into another lag's head - captured on mobile phone footage shot inside a British jail.
The stunned inmate can be seen then turning on his attacker and a brawl kicks off as other prisoners stand around and watch.
The clip was filmed by Liverpool criminal Sam Walker, and shows a prisoner approaching another inmate from behind as he walks up the stairs.
The man, with long hair, wearing grey shorts and a darker coloured jacket, swings the sock at the man before a loud “clunk“ is heard and the apparently injured inmate grabs his head.
Mr Walker posted the footage - shot inside HMP Hindley near Wigan - to his Facebook page after being released from his latest stint in prison, according to the Liverpool Echo.