HP iPAQ FA121A#AC3 Compact Flash Card Expansion Pack Plus for 3600, 3700, 3800, 3900, 5400 series Handy rechargeable, removable power Works with your iPAQ Pocket PC and the CompactFlash Expansion Pack Plus or PC Card Expansion Pack Plus products echarge with your iPAQ Pocket PC desktop cradle (not included, please purchase separately) or with the battery charger Increase your iPAQ Pocket PC battery life by 135% to 150% using this battery on your PC Card or CF Card Expansion Pack Plus Compatibility: iPAQ 3600, 3700, 3800, 3900, 5400, and 5500 series