Rechargeable battery: The lithium-ion battery allows the cordless massager to store enough energy for 2 hours of use, making it convenient and easy to take anywhere.

I can only confirm oksana.kiev's statement. Here is another answer that I wrote to another customer:

(....) the product data can now be conveniently compared under this link: https://www.galaxus.ch/de...

In principle, the two devices differ as follows: The MGS-150D has no battery operation, so it must be permanently connected to the power supply. Furthermore, the MGS-150D has additional heat and kneading massage, whereas the MGS-321 does not. Further details and differences can be found in the link above.