Politicians in Wales have decided to ban a dog and cat collar which gives a small electric shock to animals who are misbehaving.
It means anyone caught using the devices faces a fine of up to £20,000 or six months in prison.
The collars are controlled by remote control, but as the shock is small, makers said it didn't harm the animal.
The collars are designed to stop pets running into roads and discourage them from chasing farm animals like sheep.
Some experts reckon giving pets any type of electric shock is cruel.
Dog trainers say they can be very useful, provided they are used by responsible people.
But the RSPCA and the Kennel Club disagree and support the ban on electric shock collars in Wales.
The ban has come into effect straight away.