In its simplest form, a trocar is a pen-shaped instrument with a sharp triangular point at one end, typically used inside a hollow tube, known as a cannula or sleeve, to create an opening into the body through which the sleeve may be introduced, to provide an access port during surgery. The tip design of trocar instrumentation is something that is constantly evolving. The materials, edge design and transparency are factors that may facilitate placement inside the abdominal or thoracic cavity. The clear tip in the trocar above aids laparoscopic entry. Metal robot ports sit next to it on the right.