This product is a voltage converter (Step Up & Down Transformer), specifically model ST-300VA. Function: It converts voltage from 110-120V to 220-240V, and vice versa, allowing various electrical appliances to operate in areas with incompatible voltage. Capacity: This transformer has a capacity of 300 Volt-Amperes (VA), approximately equivalent to 300 Watts. Features: It includes an on/off switch, a power indicator light, and multiple output ports compatible with different plug types. Warning: It is not recommended to use this transformer with high-power devices such as hair dryers, water kettles, or irons, as they may exceed the transformer's capacity.