It’s the clamp for adding the quick release system to the DJI Ronin gimbal. You only need two parts to get the quick release function.
1. 25mm Rod Clamp MQRC-01 (DJI Ronin handlebar diameter is 25mm).
2. Monitor quick release plate (MQR-01)
With this two components, you can mount/remove the monitor, wireless transmitter from the DJI Ronin gimbal in 1 second. More important, with the 1/4 screw and front block, the device attaches to the quick release won't spin anymore. This handy tiny gear saves your time and solves your problem.