Polk Audio Camden Square Wireless Portable Speaker Full range high performance drive units-two left and two right full range drive units include rubber surrounds for long life and 19mm voice coil for better control. Passive radiator acoustic design-A pair of optimally-sized rectangular 2" x 3" mass-loaded passive bass radiators, installed on opposing faces of the enclosure, provide extended bass weight and impact. Full Complement Bass (FCB)-Below approximately 200 Hz, all drivers reproduce identical summed monophonic (L+R) signal, for optimal bass reproduction with minimal distortion. DJ Stream is Polk's app, created just for Camden Square. With the app enjoying music is more interactive and more enjoyable. With the app, anyone can get the party going as the DJ Host. Three more phones can connect and play music too, as Active DJs.