This is a Kyosho Ni-Cd battery charger. It charges Ni-Cd batteries from a 12V power source, such as a car. It cannot charge from a 100V source. It has a discharge function. It has an ammeter, so it can be used with confidence. Please note that the fuse is short-circuited. If you are concerned, please replace it with a genuine 10A fuse. Due to the above, this item is considered junk and has no warranty.