A company has designed a device which it claims will stop car thieves even if they steal the ignition keys.
Car key theft is an increasingly common method of stealing cars
Electronics experts based near Tredomen in Caerphilly spent four years developing the product.
The system works by fitting an "Invisishield" transponder in a secret location in your car - the engine only starts after brushing a fob against it.
Company Karma Innovations said it believed the device, to be manufactured in Bridgend, was an "absolute first".
Home Office research in 2004 showed ignition key theft was becoming one of the most popular methods to steal cars.
But company director Barrie Thrussell said only the owner of the car would be able to start their vehicle once Invisishield was fitted.
He told the BBC News website: "The customer decides where the transponder is fitted. It's a place where only they will know it exists and it will work under quite thick trim."
The owner of the car would keep a small fob on their key ring, Mr Thrussell said.
"If you offer that up to the transponder you have then got 15 seconds to start the car.
"You need to know exactly where that transponder is - and I mean exactly."
Mr Thrussell - a former director of the RAC's roadside services division - said it was also a good device for parents to fit if they were worried about teenage children "borrowing" the car.
"The only way you can take the car away is to put it on a transporter," he said.
'Vote of confidence'
The Invisishield has had support from the Welsh Assembly Government and Finance Wales and will be sold in association with the RAC.
It will cost about £150 and take less than an hour to fit, the company said.
Its launch has been welcomed by assembly transport minister Andrew Davies.
"The development and manufacture of this exciting new product is a vote of confidence in the electronic expertise and manufacturing capability in Wales," said Mr Davies.
"It tackles a growing problem that affects thousands of vehicle owners every year and has considerable potential to make a big impact in the UK and overseas.
Mr Thrussell added: "We know that by making it here in Wales we have a better quality product than if we outsourced manufacturing overseas."