This partner exercise called "Three Star Strikes" is practised to hardening the arms. Also can use legs to make them hard.
The picture shows the three positions of "Da Sam Sing"
Wooden Man (Mok Yan Chong) 木人樁
Exercise with the wooden man (wooden dummy) is very important for learning combat skills. With wooden man you can apply all the techniques that have been learned with the practice of the hand sets.
Iron Palm 鐵掌功
To make the palms strong and hard as iron, use the iron palm conditioning. There are many ways to do this. For example: Punching and slapping with the hand on bags many times. After this you have to use "Dit Da Jow" (Medicine) to avoid injuries.