Has your mobile phone battery ever run out when you've needed it most? If you can answer yes to this question, then the Necessorise Mo-Batt might be just what you need. An emergency mobile phone battery, the Mo-Batt is a pre-charged, disposable battery that provides up to two hours of talk time and eight hours of standby for your mobile phone.

Measuring just 75mm x 75mm x 7mm, the Mo-Batt has been designed to be inconspicuous, easily slipping unnoticed into a pocket, purse or handbag. It can be used as many times as you like, until of course the battery is drained completely. It can then be disposed of, and a new Mo-Batt can be purchased. We found the quoted battery life figures of two hours of talk time and eight hours of standby to be just about spot on.

The Mo-Batt has a cord protruding from the top right hand side of the package and this plugs into your mobile phone's charging socket. To ensure it will work for most handsets on the market, there is a package of adaptors available for the same cost as the Mo-Batt. These include adapters for most popular Motorola, Sony Ericsson and Nokia models, although not all handsets from these manufacturers are supported.

The Mo-Batt works well enough, although if you are a budding fashionista, you won't like the look of the square, bright red packaging hanging off your lovely mobile. The top of the Mo-Batt features a key ring or lanyard strap holder, so it can easily be hung off your keys or around your neck.

Overall, the Mo-Batt is quite a handy accessory, but be warned that only the most popular handsets are supported. We think its best suited for those long holiday trips, rather than day to day use, but provided you aren't concerned with looks, its convenience factor is appealing.