London - A wristband that changes colour when women are suffering from pre-menstrual tension has been designed to make men a bit more understanding at certain times of the month - or at least give them advance warning of a partner's sudden mood swings.
Dubbed 'Help for Husbands' by inventor Karl Dorn, the wristband works by monitoring subtle changes in a woman's body temperature during her monthly cycle.
The 43-year-old plasterer from Southend, Essex, has now won a place in the final of a Dragons' Den-style competition run by a local millionaire who is offering 100,000 pounds for money-spinning ideas.
In fact, the PMT wristband is more an idea than an invention at the moment as there is no working prototype and no patent.
Dorn said the idea came to him after chatting to male friends at the pub or football matches and hearing about their domestic woes.
He estimates they would sell for a few pounds and would feature a small thermometer that responds to variations in temperature by changing colour.
"It's a visual aid for men so they can be a little bit more understanding at certain times of the month," the Daily Mail quoted him as saying.
"Through my research I've found out that women's body temperatures increase at certain times of the month. This little wristband would be temperature sensitive and change colour.
"It's a very taboo issue - I was a bit concerned about putting it forward - but if you can help couples understand each other and communicate better that's got to be a good thing," he added.