I bought the power adapter together with the Brother P-touch D-400 machine. This can be used with batteries as well as with the power adapter. I decided to use the power adapter. Without batteries, however, the printed labels cannot be saved. This is not a disadvantage for me. What is important to me is the up to 3-line printout and the numerous design options. Brother recommends this adapter for my machine, but I was not at all interested in whether it would also fit other machines. In any case, I only saw this adapter when I ordered it. If other devices have the same socket, it should also fit. In any case, my device cannot be supplied with power via USB.