These are actually only 500WRMS but are 900W Peak (Max, PMPO, Music Power... Whatever)
From Alpine AU Website:
900Watts x 1 (Max Power EIAJ)
500Watts x 1RMS (14.4V, 2Ohm)
250Watts x 1RMS (14.4V, 4Ohm)
MOSFET Final Output/Power Supply
Digital Control Centre
Parametric EQ
Subsonic Filter
Time Correction
Variable Crossover
RCA Buffered Pre-Out
Input Level 0.5V ~8.5V