This is the updated version of the Pure battery pack, first available at the start of December 2007. I am using it with a Pure One radio.
It is a package the same size as 6 C type batteries, with a short cable and connector at one end. You plug the connector into a mating connector inside the battery space at the back of the radio, then fit the battery pack into the battery space. This is easy to do. Once fitted, the radio operates with or without mains power being connected. Whenever power is connected, the battery pack charges up and the radio operates from mains power.
The instructions recommend a 24 hour charge initially, which I did though the indicator suggested it was fully charged long before that.
In use I found it lasted for about 20 hours before the radio died. The indicator sits at 4 bars for most of this time then drops off quickly. From the drained state it took about 10 hours to charge again. However, I find it easier to keep the charger at my bedside and plug the radio in each night, so it does not normally fully discharge. This way, it is fully charged by morning and can be used anywhere in the house during the day for as long as needed, without running out of power.