iPod 2 Speaker add on Unit (use with WP-RZ3O4) Increase the output of your WP-RZ3O4 overhead audio system. Provides hi-def stereo sound by adding 2 more 6.5 Inch marine speakers to your speakers staged directly over head. The amplifier in your main unit is 50x4. This add on utilized the 2nd half of that amplifier. Includes brackets, hardware and instructions. Simply wire in speaker harness to your current unit then connect to the speaker add-on. Works with most roofs.