RTP4000 Party pack contains:

RT501 amplifier 500w RMS @ 2ohms
double 12" enclosure

RT12x2DV Slotported enclosure :
High output MTX Slotported Enclosure
Vented enclosure with ROADTHUNDER subwoofers
Unique slot port design
Designed to deliver loud and accurate bass
Spider Plateau Venting (SPV)
Asymmetrical Linear Drive System (ALDS)
Spring loaded connection terminals for easy connection