Basicly Power cords are rated at different Gauges. The higher the Gauge the smaller the cord, and the lower the gauge the thicker the cord is. The Thicker the cord is the more power it can transfer without losing its efficiency with length. I don't know what the wattage draw on the metabo is, so I can't help you choose which one would be most suitable for you though. You order them from walmart or sears, but Hardware stores like HomeDepot and Lowes would probably suit you better. I would also sugest an outdoor cord because the cover around it is thicker, so It will last you a longer time.
Hope this helps you in anyway, I'm not quite sure what information you are looking for.