The shunt is separate from the meter, it is a 100A/50mV shunt and gets wired to the meter with a twisted pair wire (not-included) to avoid picking up interference along the way. There is no specific length stated for the length of this wire but extreme lengths would presumably result in a loss of accuracy. The shunt is also sold separately as p/n 9230. If you go to the Blue Sea web page for the shunt you will see this message: "For continuous operation, it is recommended that shunts not to be run at more than two-thirds (66%) the rated current under normal conditions