They are weapons that kill that can't be bought in shops. So why is it so easy to buy zombie knives online?
ITV News London has seen evidence that getting hold of these banned knives takes a matter of days and costs just a few pounds.
We can reveal that they can be bought illegally online in just a few clicks with no checks on who is buying them and whether they are children.
The Mayor has told ITV News London there is 'no justification' for that. Ordering banned knives online is illegal.
The charity Lives Not Knives filmed the process. Eliza Rebeiro contacted ITV News London with her concerns.
What's more the knife arrived under false pretenses.
Eliza handed the knife over to the police and ITV News London made contact with the Home Office and wish.com.
What checks and balances are in place at Border Control was one question to the government. And to wish.com - a marketplace that hosts various vendors - why so many different types of weapons available for purchase without thorough checks?
The Home Office said: "The Offensive Weapons Bill currently before Parliament, will make it an offence to possess certain offensive weapons in private and stop knives being sent to residential addresses after they are bought online."
And, on border control they said officers undertake targeted examinations.
Letitia and Abigale have both felt the devastating impact of knife crime.
With the internet now a go-to place for buying things there will be a spotlight on whether the law is strong enough when it comes to offensive weapons. As everyone who is part of the charity Lives Not Knives knows - they change lives.