Brunton Bear the Brunt - Power In The Field
The devotees of action photography with the ever-popular GoPro Hero 3+ camera sometimes find that the best action occurs after the camera battery runs out of electricity - certainly the best language is heard...
To obviate this, Brunton have made a clip-on rechargeable lithium cell pack that they say will give 4 x longer operation with this model of GoProHero 3+ back and clip this one on. They emphasise that it is water-resistant only - do not submerge it.
It also seems to have a 3-way cable included that lets you access the power for a number of iDevices.