In ancient Traditional Chinese Medicine, the cups were made of bamboo, animal horns or pottery. Nowadays, practitioners use cups made of glass. This helps them see how the skin looks like inside of the cup and it gives an idea on how the cupping treatment is proceeding. During a cupping treatment session, the practitioner soaks a cotton ball in alcohol and then creates a vacuum inside of the cup by burning the cotton. The burning is done in order to use up all the oxygen present inside the cup, this creates a partial vacuum inside of the cup that is then placed on the surface of the skin in a specific acupuncture point accurately chosen by the practitioner. Under the clear glass cup the practitioner can see how the skin is lifted turning red or purple. It is usually left in place for 10 to 15 minutes depending on the case situation and therapeutic need.