The family of a teenager who suddenly died are taking part in a campaign to get defibrillators fitted in all Welsh schools.
Jack Thomas, 15, of Oakdale, Caerphilly county, died unexpectedly in 2012 while watching rugby on TV, with cardiac arrhythmia thought to be the cause.
The number of defibrillators in Wales has increased by 75% over the past two years, with 3,402 available.
His family has teamed up with Welsh Hearts to extend this to schools.
Jack's mother June said: "Jack was a fit and healthy boy who had represented Wales all across Europe on a number of occasions in Taekwondo.
"Jack was an A* student and had been successful in gaining a scholarship at Cardiff Sixth Form College.
"Jack's death came as a complete shock to us, as Jack had never been ill."
The 15-year-old died while watching Wales play a Six Nations match on TV. He had no injuries and no damage to his heart or arteries, but a pathologist at his inquest said it was likely his heart beat out of control, known as cardiac arrhythmia.
Welsh Hearts say that if a defibrillator is used in conjunction with effective CPR within 3-5 minutes of a cardiac arrest, it can increase the victim's chance of survival from 6% to 74%.
Without immediate treatment, 90 to 95% of sudden cardiac arrest victims will die.
It is estimated 270 children in the UK die of a cardiac arrest in school every year.
Across Wales, there are 3,402 defibrillators, a 75% rise 1,929 pads in January 2017.
The Welsh Ambulance service said defibrillators were "essential" for communities across the country.
The Welsh Government said: "We have helped the Welsh Ambulance Service to install and promote defibrillators across Wales and are working with charities to place new ones."