The Pro-HG Duo, actually produced together with SanDisk, is designed to accommodate the faster write speeds needed to record high-resolution digital video and photos to a Memory Stick. This is achieved through increasing the number of channels in the physical interface between card and reader to 8 bits. Essentially, this means more data can flow at any one time.
The new maximum data transfer rate is 480 Mbit/s, which is three times faster than Memory Stick Pro cards can manage. To ensure backwards compatibility with products that have slots for current-generation Memory Sticks, the old 4-bit interface has also been included in the card.
This dual interface is sure to mean the HG cards will be expensive when they launch next year. Lastly, the new cards have a much higher maximum capacity than current Memory Sticks - up to 32GB is possible, although Sony points out that this is no guarantee such cards will ever be sold.