Tubular copper cable lugs across the sizes a battery bank actually uses: cross-sections of 10mm², 16mm², 25mm², 35mm², 50mm², 70mm², 95mm² and 120mm², each with M6, M8, M10 or M12 ring holes depending on the size.
Two measurements have to match, not one. The barrel is chosen on the cable cross-section and the ring on the terminal stud: 10mm² is offered with M6, M8 and M10, while 120mm² starts at M8 and goes to M12. A lug that fits the stud but not the cable is the usual cause of a warm joint.
Work out the stud size on the battery and the inverter first, then order the barrel to suit the cable you are running.
