It is a technique to wrap your lower collar around the opponent's neck and squeeze it while controlling the opponent's arm with a firm stomach. It's a choke that hasn't been used much yet, so I think many opponents will panic for a moment and it will be difficult to properly defend. In Crucifix, you control by entwining your foot around the opponent's arm, but be aware that the subsequent development will change greatly depending on whether you put your left or right foot on the opponent first.
This video shows how to use it when you first put the foot closer to the other person's lower body. By using this foot, you can reduce the risk of getting entangled like a half guard, and there is an advantage that it becomes easier to keep for a long time. There are also tips on how to squeeze after wrapping the lapel, so be careful not to pull it with force and get your arms tired.