Dtk Laptop Battery for Compaq 320 321 325 326 420 421 425 620 621 625 ;For Hp 420 425 620 625 Probook 4320 4320s 4321 4321s 4320t 4325s 4326s 4420s 4421s 4425s 4520 4520s 4525s Notebook Battery type: Li-ion; Capacity: 4400mAh; Cells: 6-cell; Voltage:10.8V. 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.