This cunning karabiner that looks like a knuckleduster actually does away with the need for a rigging plate and multiple locking krabs at a belay.
It will be found particularly useful by aid climbers who will be able to construct a belay, clip themselves into one loop, the haulbag into a second and belay their partner from the third. It could also be handy for instructors bring up multple seconds.
Use of Grivel's Twin Gate system makes it effectivly a locking karabiner even though there is no locking mechanism - once mastered this is very easy to use as only one gate needs to be opened for any task.