These can be used with reverse direction pump impellors where an alternator / power steering pump is needed as they are machined to suit a 6pk belt. Diameter is increased to 130mm These reduce pump speed by 20% to help reduce power loss and and pump cavitiation at high rpm. Fully CNC machined in aluminium and weigh in at 65g less than the std tin item and come hard anodized in black. Uses std bolt fitment.