Infusion sets contain thin plastic tubing that delivers insulin from the pump to your body. This tubing comes in different lengths to accommodate different needs. At the end of the tubing is either a soft, flexible cannula, which is a small, tapered tube, or a stainless steel needle. The cannula is inserted under your skin, in a spot such as your abdomen, thigh or buttocks. This spot is called your infusion site, and it remains in place for up to two or three days.