Hello @SI07AM, 'm not sure to get understand your question. Pair is the main entity defining the contact. It requires the definition of master and slave entities through surfaces. Then you can also link you contact pair to a surface interaction keyword to define some parameters such as friction
@@altairhowto Thanks for your answer. I still have doubts. I explain myself better. In Contacs you have 3 options: Surfaces, Pairs or Properties. Wich is the difference between to choose Surfaces or Pairs? That’s my question.