Don't buy this one if you aim using it on a Genesis 1 or Sega CD unit. This is a cheaply constructed switched power supply, the same kind you use to charge a cell phone. By the weight (extremely light) you will notice something is wrong and indeed it is. Switched power adaptors have a lot of noise which must be filtered, but the Genesis is not prepared for that so you'll be playing with a nice "buzzing" noise all the time (great huh?). Last, it's targeted to Genesis systems but the max current it supports is 850mA, when the console demands 1200mA so expect it failing soon. Garbage!