The best model Norelco to use is the Aquatec. You can buy a replacement BODY including batteries for about $20 on Ebay. You can also purchase a complete used replacement razor for about the same price for $20 on Ebay. The problem with Norelco is it requires replacement of the cutter heads each year and it turns on an orange warning light on the razor body to remind you. The razor continues to operate normally except for the warning.