Panasonic SB-WA500 Wireless Subwoofer. Turns on but cannot test it because I don´t have the soundbar. (Just the Subwoofer). 
Item looks in very good condition and have some light scratches. Please see pictures.

This Item needs Sound Bar SB-HTB500 to test it. I don´t know much about it, just that when I plug it and press de Power button, the red light turns on.