The ZR212LD provides dual 12 inch subwoofers loaded into a ported box for the listeners who like it loud! MOTOR Voice Coil Diameter 1 / 25.4mm Voice Coil Former Material Kapton Winding Material Aluminum Diaphragm Material Polyester Magnet Material Neodymium Magnet Weight 2 Oz Body Material ABS Body Color / Finish Black Matte. MEASUREMENT Overall Diameter 3" / 77.2mm Overall Depth 2" / 52.5mm Front Mount Baffle Cutout 2.25" / 57mm Mounting Depth 1.87" / 47.5mm Motor Diameter 2.2 / 56mm. The ported box is tuned to 29 Hz and helps get the most from your subwoofers by delivering a deeper, punchier bass. Included in the ported box are two ZR12.4D subwoofers, one of our bestselling car audio subs, designed with dual 4-Ohms voice coils wired in parallel for a nominal impedance of 1-Ohm. This loaded subwoofer combo offers great sound through high-quality and high-power subwoofers in a prefabricated box that is guaranteed to last! The box is constructed of thick 3/4 inch MDF for great strength, resonance, and tuned to 29hz for low and hard hitting bass. Dual 12 inch car audio subwoofers with the cone area to blast great sounding bass more efficiently Subwoofers.