Redrock Micro's microMatteBox Clamp Assembly for ultraCage DSLR attaches to the side of an ultraCage DSLR to let you mount a microMatteBox from the side and to thus keep your bottom rails free for other uses. The Clamp maintains proper mattebox height and allows the mattebox to properly swing away. Alternative to attaching a mattebox, you can simply attach 15mm rods or any accessory that sits on 15mm rods, as long as what you attach can serve useful mounted on the side of the cage.