The PowerPak allows you to put NES ROMS on a Compact Flash card (CF Card).   If you already own a CF card, or know of a camera store or electronics store that sells them cheap, then you may not need to get one.

Also, if your computer already has the ability to read and write to the CF card, then you would not need to buy an external USB card reader.

In my case, my printer has a number of card slots, including a CF card slot, so when I put a CF card in my printer, my computer shows it as a new drive, and I can just write to it that way.

If you do not own a CF card, or the ability to read/write to it, you will need to purchase  both of those to use the Power Pak.

Edit-  it is my understanding that the PowerPak contains a Ciclone chip, which allows it to run on any type and region of NES, without needing them to be modified.

Al

This stuff is over my head, lol.