Nikon BR-3 and BR-2 Macro Reverse Filter Adapter Ring Set [EXC+]
This is a very cool setup for shooting macro without a macro lens. With the BR-2, you can mount your Nikon lens backwards for macro capabilities, and with the BR-3, you can mount filters to the mount-side of your lens.
If you want to shoot macro on your current lens setup, this is what you need.
Both units are in excellent condition with very little wear.