It’s all too easy to lose track of how much you are spending.
But now an inventor has solved the problem with a set of “smart” wallets that actually tell you when you are low on cash.
One of the “Proverbial Wallets” actually shrinks when your bank balance is low in an effort to discourage you from spending.
Another has a hinge which becomes tighter and tighter to open when you have less money whilst a third vibrates every single time you use it, reports the Daily Mail.
The wallets were developed by product designer John Kestner who works at the Massachusetts Institute of Technology (MIT) Media Lab in the US.
They are currently at the prototype stage but, should banks or consumers take an interest, the designs could be put into mass production, he said, according to an MIT statement.
All three wallets have a tiny computer inside them and use a Bluetooth connection to the individual’s mobile phone which then connects to the Internet and their bank account information.
This means that the wallet is constantly updated with how much money the user has in his account, and can act accordingly.