Specifications: Capacity: 4400 / 6600mAh Chemistry: Li-ion Voltage: 10.8V Cell: 6 / 9 cell Compatible Models: HP: HP 420 HP 425 HP 4320t HP 620 HP 625 HP Compaq 320 HP Compaq 321 HP Compaq 325 HP Compaq 326 HP Compaq 420 HP Compaq 421 HP Compaq 620 HP Compaq 621 HP ProBook 4320s HP ProBook 4420s HP ProBook 4425s HP ProBook 4520s HP ProBook 4525s HP ProBook 4321s HP ProBook 4325s HP ProBook 4326s HP ProBook 4421s Please carefully check your battery's Compatible Model & battery picture to ensure compatibility with your Laptop. What's in the box 1 X Astrum Replacement Laptop Battery for HP ProBook 4320 4520 4420 4720 4525