Each pendant has a unique code which is logged on the police computer system. Police can also hold extra information about users of the system that helps search teams to find missing people faster.
On Monday night the family reported the 77-year-old missing about 10.30pm. He had left the farmhouse on a rural road near Hukerenui and they were unable to find him.
It wasn't until officers in the Search and Rescue squad and members of the LandSAR team, trained in the use of the tracking equipment, arrived that they could get an idea of where he had gone.
Constable Jim Adamson, officer in charge of the operation, said the temperature was about 8C and fog meant searchers could only see a few metres ahead.
Teams searched through paddocks and along the edge of native bush. After one-and-a-half hours he was found lying in a paddock, just off a farm track.
"He was cold and wet and hypothermic and completely lost. Without the [Wandatrak] equipment there's a possibility we wouldn't have found him that night and he may not have made it through to the morning," Mr Adamson said.
The man was treated by St John ambulance staff at the farmhouse.
The tracking gear was back in use yesterday after the man went wandering while on a shopping trip with his daughter at The Warehouse. Police said officers began searching after he walked off about midday and a search by the family failed to locate him.
Shops in the area were searched but he was not found.
Mr Adamson said police then went up Parihaka with the tracking gear and were able to determine the man, while always on the move, was in the Regent area. From Parihaka Mr Adamson was able to get those searching to refine the area until it was narrowed down to Hatea Dr where the man was found just before 3pm.
In 2013 the first Wandatrak was issued in Northland. There are now 16 in the Whangarei and Kaipara area and about 10 in the Far North area.
Northland SAR volunteer Grant Conaghan said anyone who suffered from Alzheimer's, dementia, autism or was likely to wander off for lengths of time and put their safety at risk would benefit from using a tracker.
"This technology reduces the time spent searching and the number of people needed. It's reassuring for families who may have a loved one who wanders off."
It's estimated more than 60,000 New Zealanders live with dementia, a number that's expected to triple by 2050.
The Wandatrak devices are not funded by the Government and the WanderSearch group distributing the pendants in Northland relies on donations to provide the devices.
For more information contact northlandwandatrak@hotmail.co.nz or wandersearch@fnsar.org.nz