Police have released images after a series of robberies took place in central London.
The eight robberies and attempted robberies occurred between Wednesday, July 21 and Friday, July 30.
During each robbery, two black men on electric bikes approached their victim and demanded that they hand over their watch.
On several occasions, a firearm was produced.
In one incident at 11.26pm in Addington Street, at the junction with York Road, Lambeth, the victim was struck with a pistol and sustained injuries to his head.
He was taken to hospital for treatment but was not seriously injured.
The eighth robbery took place on Friday, July 30 about 8.30pm in Hyde Park when the victim was approached by two suspects on e-bikes.
One of the men brandished a firearm and told the victim to hand over his watch, estimated to be valued at £140,000. The suspects then fled the scene with the watch.
The suspects are described as black men, between the ages of 18 and 25, wearing all black clothing.
They were both seen to be riding black electric bikes and had their faces covered, the force said.
Detective Constable Tom Waller, the investigating officer from the Met’s Operation Venice Investigations Team, said: “These robberies were absolutely terrifying ordeals for the victims and we are determined to do everything we can to bring those responsible to justice.
“The suspects are dangerous individuals, as they have proven by repeatedly brandishing a firearm, and I would appeal to the public to help us get these men off London’s streets.”
Anyone with information is asked to call police on 101 quoting Operation Kimax.