When Mark Allewell's twins lose the TV remote control, he finds it with his cellphone. The 42-year-old Cape Town inventor is behind a coin-size tracking device that has just gone on sale after two years of development.The R449 Bluetooth-enabled Sensor can be attached to keys, bags or dogs and once it is paired with your cellphone it helps you to stop losing them in the first place - and to find them if the worst happens.The device has a light and an alarm that can be activated by the app on your phone, functions Allewell finds useful when his five-year-olds "hide" the remote. He hopes the device, which is 100% South African, will form part of a data-gathering network that will help other Sensor users to find their belongings.Once the Sensor falls out of the phone's Bluetooth range - which can be up to 90m - it saves the location and automatically notifies the user."When you disconnect it saves that last address so you will know where it was last left. You can mark it as lost and then everybody else with the app on their phone as they walk past will be able to find it," he said. Information from each device is fed into a network and users are told when they are at risk."The idea is to stop people losing or having their stuff stolen in the first place. We are working with insurance companies who are monitoring that data to see how people interact with stuff."The data would help insurers to decrease their risk and he hoped the product would soon be included with their policies.Allewell is also the creator of Tourist Radio, a device placed in a taxi that tells people what they are looking at while driving through a foreign city. He recently bought Zapacab, a hailing service that allows taxi firms to compete with Uber.Last month he was one of 20 "up-and-coming" South African entrepreneurs, including radio presenter Gareth Cliff, who were taken to Silicon Valley in San Francisco by En-novate and Investec, to expose them to global opportunities."Mark's business impressed us, as it has a very practical applicability. It is a product that many of us would use," said En-novate co-founder Dan Brotman...