Detectives investigating the London Bridge attack have released images of the terrorists' fake suicide belts.
The realistic-looking phoney bombs were actually disposable water bottles wrapped in masking tape.
The belts, worn by attackers Khuram Butt, Rachid Redouane and Youssef Zaghba on their rampage that killed eight people, and injured dozens more, were designed to create "maximum fear", Scotland Yard said.
The terrorists were wearing the belts when they were shot dead.
Commander Dean Haydon, who is leading the investigation, praised the bravery of the armed officers who shot the attackers dead despite the possibility they could have been killed in an explosion.
He said: "I have not seen this tactic in the UK before where terrorists create maximum fear by strapping fake explosives to themselves. Anyone who saw them on the night would have thought they were genuine.
"It is hard to speculate what the motive was for wearing the belts. It could be that they had plans to take the attack into a siege situation or it might be that they saw it as protection from being shot themselves.
"It makes the bravery of those police officers and members of the public who tackled the terrorists even more remarkable. The belt would have been visible to them and if you are fighting back or aiming a shot at someone wearing the device, you would clearly be very aware that you could be caught in an explosion."