Built to resist high-powered weapons and explosives, the caveirão has two layers of armoury, as well as a steel grill for protecting windows when under heavy fire.It weighs around 8 tons, the caveirão can reach speeds of up to 120km an hour. Its tyres are coated with a glutinous substance which prevents punctures. Its four doors lock automatically and cannot be opened from the outside two escape hatches, one out of the turret and the other in the floor can be used in emergencies.
Police officials claim the caveirão is essential for the protection of officers on dangerous missions. The Rio authorities have bought 10 caveirões, at a cost of R$135,000 each (approx. US$62,000), to police Rio's shanty towns, with plans to increase the fleet in the coming years.
In response to the caveirão, drug gangs have reportedly been buying sophisticated grenade launchers and high-powered rifles to penetrate the caveirão's armoury. In the favela of Inhaúma, the BOPE reportedly found a manual, written by drug traffickers, on how to combat the caveirão with chapters on types of explosives effective against the caveirão, methods of attacking the vehicle and instructions on urban guerrilla warfare.
When the caveirão approaches someone in the street, police shout through the megaphone: "Hey, you over there! You are acting suspiciously. Move very slowly, lift up your shirt, turn around... now you can go". Loud-speakers mounted on the outside of the vehicle repeatedly announce the caveirão's arrival. Expressions used vary from the polite: "Residents, we are here to defend your community. Please, don't go out of your homes, it's dangerous"; to the alarmist: "Children, get out of the street. There's going to be a shootout"; to outright intimidation: "We have come to take your souls".