This invention consists of a sock, a sending unit, a receiving unit, a sensor light, and a line that can be connected to a pulse-oximeter cord. A medical professional places the sock over a patient's foot and adjusts its position until the equipment is properly aligned. The cord from the pulse-oximeter can then be attached to the line from the sending unit. The sending unit activates the sensor light that emits radiation at a minimum of two wavelengths. The receiving unit detects the radiation after it passes through the skin and produces an electrical signal in response to the radiation that can be decoded by the pulse-oximeter.