You are not permitted to download, save or email this image. Visit image gallery to purchase the image.
Administered by Dunedin-based volunteer Kay Raw, the system employs a small radio frequency transmitter, which can be worn as a neck pendant, on the wrist or on a key ring.
If the wearer goes missing, the device can be activated and its signal picked up by police and search and rescue volunteers using a mobile receiver.
Operated under the umbrella of the national WanderSearch programme, the devices are part of Dunedin's "Safer Walking Programme''.
Ms Raw said the New Zealand-made devices were suitable to be worn by people of all ages with a range of possible cognitive impairments, including Alzheimer's, dementia, autism and head injury.
"They are another very useful tool in the toolbox, when you are out searching for someone who may have become confused and lost,'' Ms Raw said.
Employing a WandaTrak device potentially reduced the amount of time it took to find a missing person from about eight hours down to about 90 minutes.
"That could be very important in Dunedin, where it can get very cold and dark,'' Ms Raw said.
Dunedin has 13 of the WandaTrak devices employed, but a recent boost in national funding means a further 12 have been allocated to Dunedin.
In addition, a request for funding from Lodge St Patrick in Dunedin was successful, with a donation of $600 from the lodge covering the cost of another two devices.
Lodge St Patrick Master John Hazeldine said the group was happy to support such a good cause.
"These devices are a great asset for the community,'' he said.