1.safe enough 2.easy operating 3.convenient and light 4.cheapest it's a mini Ultrasonic Cleaner , very easy to operateso let me introduce how to use it first link the power,second then the switch on third , put a bit water in it to cover the bottom like in 2 mm fourth , then hold a cartridge make the toword the round of the bottom but not touch the bottom , then in less then 1 minute.fiveth , ...