Lanparte's nifty little DRC-02 allows you to attach any accessory with 1/4-20 thread to your 15mm rails. This is great for microphones/sound recorders, small monitors, and anything else you need to attach to your rig. This could also be used by attaching this straight to a cage to allow for 15mm rails. If your cage does not have 15mm rail support, add this little accessory and away you go.
Weighing just 63grams, you won't even notice its there :)