ALDS Technology SPV Technology Spider with interlaced tinsel leads Original MTX steel frame One piece Polypropylene cone Butyl rubber surround �50 mm high temp (220�) aluminium voice coil High-end, heavy duty Streetwires terminalsThe looks of this entry level sub tell exactly what's in store! Powerful Accurate Bass at an unbelievable price point. This woofer shines when used in a sealed enclosure and causes a small earthquake when used in a vented enclosure.