Swap out your optical drive with a second battery to increase your unplugged power supply the thinkpad advanced ultrabay battery iii fits neatly into the ultrabay media bay of thinkpad t400 series t500 series r400 series t410s series r500 series w500 series t60 series z60 series select r60 series notebooks and is compatible with the thinkpad x6 ultrabases achieve all day computing up to 8 hours or more when you use the thinkpad advanced ultrabay battery iii along with a high capacity