Welcome to the forum Stuart As Arry says the rear one is the baitrunner. You cast out and put the rod on your rodrest. You then flick the lever above the rear knob. When a fish takes it can run at the tension set on the rear control and take line. When you pick the rod up and start winding the baitrunner lever will flick back and the tension will change to that set on the front clutch. You want to set the front tension high and the baitrunner tension low. Hope that makes sense.