DENAQ 6-Cell 4400mAh Li-Ion Laptop Battery Compatible with Multiple ACER Models including Aspire 2420, 2920, 3620, 3640, 3670, 5540, 5550, 5560, 5590; Extensa 3100, 4120, 4220, 4420, 4620; Ferrari 1100; Travelmate 2420, 2440, 2470, 3240, 3250, 3280, 3290, 3300, 4320, 4520, 4720, 6231, 6291, 6