I usually use the RRS L bracket on my H4D but if I want to use the GIL attachment then the L bracket doesn't' fit. So I have found the RRS 27D works very well. It looks very like the one suggested by Wayne, probably slightly different size, but same idea. I have no Idea why I have a 27D. Obviously fitted a camera, or lens, I once had but have parted company with. It may be that it is no longer made but I find the style works very well and is very neat.
Regards
Richard