Dtk New High Performance Laptop Battery for Dell Studio 1535 1536 1537 1555 1557 1558 Pp33l Pp39l Wu960 Wu965 Mt276 Mt264 Km905 Pw773 Km904 Km887 Km958 312-0701 Replacement Notebook Battery (11.1v 4800mah 6cells) 12 Months Warranty Battery type: Li-ion; Capacity: 4400mAh; Cells: 6-cell; Voltage:11.1V. Grade A cells ensure fast charges and low power consumption; Built-in circuit protection ensures both safety and stability. 100% New from Manufacturer. Up to 500 recharge cycles over the life of the battery. 24 x 7 email support, 12-month hassle-free warranty. Operation time for standard batteries(6-cell, 4400mah): Around 2 hours, the actual operation time will depend on how much electricity is required by the device and how you use it.