Rockustics - SquareRoot 6.5 - 6.5" 2-Way Loudspeaker Planter (Single) A fully functional 20 inch (508 mm) square planter with drainage holes, the SquareRoot 6.5 is an omnidirectional 2-way speaker as well. It includes a 6.5” coax woofer and .75” dome tweeter. An optional 64-watt transformer is available for installation of the SquareRoot in 70 volt systems. SquareRoot planters are constructed of UV-stable, rotation-molded polyethylene and are available in two colors.