Monitor, PM4, B/C discontinued by Concept 2. The substitute for this part is CON1832 (OEM# 1832) for Model B Rower or CON1833 (OEM# 1833) for Model C Rower.
PM4 Monitor:
Port for the optical Polar™ heart rate receiver.
USB port for connecting the computer. Beveled corners on USB cable plug face the back of the monitor. DO NOT FORCE when plugging in.