This eco-friendly product has an internal lithium-ion battery that can be recharged approximately 500 times. There are two temperature settings to choose from and a microcomputer enables high-precision temperature control preventing burns. Temperature setting and operation status are indicated by LED color and blinking. During normal operation, the LED blinks softly and rhythmically as if breathing. In addition to the warmth you feel through your palms and smooth touch of the gently curved surface, the tenderly blinking LED softens your heart visually. The aim was to create a simple and gentle design to be cherished for a long time.