I have one of these too, but it won't work on the male M401 battery, unless I'm doing something wrong. I tried it and the battery wouldn't stay in. So female batteries only for this I think.
It works fine on my KR808D-1 and 901 batteries... which are both "male" ends. But they are larger in diameter than the M401 I believe.

I've been looking for a powered usb hub like that. Am I correct in guessing that it doesn't need to be plugged into the computer? just into the wall? If so, what is the brand and where did you find it?