This read-write value, in meters up to 70, sets the cable-length threshold the switch uses to decide whether a port qualifies for Short-Reach power savings. Admins tune this if their cabling environment doesn't match the automatic cable-length detection, ensuring the feature only applies power reduction to genuinely short runs. For example, setting this threshold to 20 meters means only ports whose detected cable length falls under 20 meters will get the reduced transmit power treatment.