This extension speaker can plug in to a main Focus 505 portable PA system (not supplied) to double up on sound and improve coverage. It is powered by its own internal battery therefore it will not affect the battery life of the main unit.
It can be also used with any other brand of portable PA system with the "extension speaker" output (6.5mm jack).
Full Technical Specifications available on http://www.chiayo.com.tw/english/focus505.html