Use Compact Flash Cards on your Sony PSP. Allows you to effectively use larger and cheaper CF cards. Also allows you to plug in a Memory Stick (even older outdated larger sizes) using its pass-through port, hence the 2in1 product name.
Product Features
Supports Compact Flash Cards or Microdrives on Sony PSP
Supports Memory Sticks without unplugging the device (pass-through)
Supports flash cards and drives with up to 4.0GB