QSC Audio HPR122i, HPR152i, HPR153i, HPR151i, HPR181i : - QSC HPR Series Powered Loudspeaker Products HPR122i 12-inch two-way, HPR152i 15-inch two-way, HPR153i 15-inch three-way, HPR151i 15-inch subwoofer, HPR181i 18-inch subwoofer User Manual : Page 19