Police are arming themselves with sponges to help clean up the streets.
From tomorrow some specialist police units will have a new non-lethal "sponge round" added to their arsenal.
The 40mm projectiles have a high density sponge nose designed to spread its energy across 4.5 times the surface area of a bullet.
The rounds will pack a punch, however, causing pain, bruising and abrasions when they hit a person.
Police media adviser Ross Henderson said the impact is unlike any other projectile.
"The impact from the sponge round is probably best described as like a hard punch.
"It can't be compared with a paintball because it is of a very different shape and design."
It is designed not to penetrate the target and the reaction it generates will vary depending on range, state of the person (whether or not affected by alcohol or drugs) and other conditions at the time, Henderson said.
It will not be a standalone option, rather it will be used in conjunction with a range of other tactics, like dogs and Tasers, he said.
The sponge round is manufactured by American company Safariland.
Its website lists its velocity at 99 metres per second, roughly the same velocity as a typical paintball shot.
It describes the sponge as an excellent solution to incapacitate a single subject or control a crowd.
"It is most commonly used by tactical teams in situations where greater accuracy and deliverable energy is desired for the incapacitation of an aggressive, non-compliant subject at longer distances," the website said.
The optimal range is five to 36 metres, although it may be used in situations from two to 50 metres, the website said.
They are fired from a 40mm gas launcher already available to police and will be used by the Auckland, Wellington and Christchurch Armed Offenders Squad (AOS) and national Special Tactics Group (STG).
Police National Tactical Groups Commander, Superintendent Bruce Dunstan, said the rounds will be used in situations where previously guns may have been the only remaining option.
"This supplements the variety of tactical options that are already available to us during callouts, as the rounds provide a mid-range option that helps enhance staff and public safety."
Police consulted with the Independent Police Conduct Authority (IPCA) and other interest groups before introducing the sponge round. Their use has also been independently reviewed by researchers, Dunstan said.
"While any use of force by police carries an element of risk, the conditions under which any tactical option may be used will always be dictated by the actions and behaviour of those we are confronted with at the time," Dunstan said.
"That said, use of the sponge round is expected to be relatively limited, given that it is only available to a few specialist groups, and that it will not be viable to use in every situation."