Portable “top-up” or emergency chargers have been available for mobile phones for ages, but they tend to make using your phone difficult. When it’s tethered to the external battery and you want to use the phone for a call, you also have to lift the attached battery.

Designers Sang Hoon Yoon and Hyeji Eom came up with an elegant, streamlined top-up battery concept that gives you double the charge time and half the hassle. The Wireless Dual Battery starts out as a disc-shaped object. When you want to use it to charge your phone, you simply pull the halves apart and plug the half-circle into your phone.

The slimline charger fits right in with the phone’s body and lets you talk while charging without the awkward cord or clunky portable charger. If you’re feeling generous, you can even charge your phone and give the other half to a friend to top up at the same time.

When the Wireless Dual Battery is charging, the two halves fit together to charge at the same time. The charging pins slide to the sides so the halves can click into place. The design is clearly meant for an iPhone, but if the charger ever makes it into production we hope it would be offered for a wider number of devices.