Gwai Jaang is one of the elbow techniques we have in Wing Chun. It's traditionally introduced at the Biu Ji level and Gwai Jaang actually in Cantonese means "kneeling elbow." Literally, as if you were kneeling on the ground. The reason we call it a kneeling elbow is because it's a little bit different from the other elbows we have in Wing Chu. The standard elbow we use in defense is called Pai Jaang which means "hacking elbow" and that is basically anytime you are close and you are hitting somebody with an elbow here either in the throat, or the chest, or the face, or to the outside. That's your kind of standard bread and butter elbow in the Wing Chun system, but Gwai Jaang is done a little bit differently. Gwai Jaang is normally used to control your opponent's arms at the same time you deliver the elbow strike. So, for example, if we use Chi Sao as an example. If my arm is above his arm here, I can use the Gwai Jaang to actually control his arms here. At the same time I'm hitting him, the kneeling position of my arm allows me to control his arms at the same time. So, I don't necessarily need a secondary hand here to control him. I can actually control with the elbow, and my other hand is here free to punch. So this is what they mean by kneeling elbow. It drops down, your shoulder has to stay low, elbow stays low, and it's actually going to control the arm like this. When it's practiced, the elbow should use the waste force to generate power and should drop a little bit too because this is actually what gives the controlling effect of the Gwai Jaang.