Armed police in London will be given head-mounted cameras to boost transparency - more than three years after the idea was originally put forward.
The Metropolitan Police said around 1,000 officers working for armed response units will have the devices attached to baseball caps and ballistic helmets.
The plans were first suggested by previous Met commissioner Sir Bernard Hogan-Howe in 2014, in the wake of the death of 29-year-old Mark Duggan, as a way of ensuring speedier justice for victims and greater accountability.
Mr Duggan's fatal shooting by a police marksman sparked nationwide riots.
Commander Matt Twist, in charge of the Firearms Command, said the cameras will provide "a documented and accurate account of the threats officers face and the split second decisions they make".
He added: "The cameras also offer greater transparency for those in front of the camera as well as those behind it."
Only those officers who carry a firearm overtly will be given a camera, while other units including Mounted Branch, Parliamentary and Diplomatic Protection and Specialist Crime Units are to be given the devices by October.
London mayor Sadiq Khan said the technology "will make a real difference to those carrying firearms"
He said: "As we complete the London-wide rollout, the cameras will also provide our officers with confidence in the transparency of their actions, as they continue their great work on the front line fighting crime and keeping our city safe."