The LED lamp quickly unpacked and tested on the dark balcony: First impression, it is only useful if you have no backlit keyboard. The light is to read an A4 page is too low. The base has to be weighed down with inserted batteries, otherwise it falls over. In battery mode, however, the brightness due to the 1.2V battery voltage even lower. Since missing the 0.6V. One should operate the lamp for the brightness loss only to USB. Whether the batteries are also charged here, I have not yet tested. The socket on the lamp has a built-in contact switch. Sometimes lifting the USB connector from the Macbook, the lamp goes out. In battery mode then you have only the power supply plug from the lamp pull. The lamp is for the price but more a toy. For the low price it's not worth it to send the lamp back. Who has written the many positive reviews? My suggestion: Build an LED lamp with built-in battery and with more powerful LEDs. There's also enough power to the USB port available.