It bypasses the need to copy files to an SD card first, which is helpful if your card is formatted to (which has a 4GB file size limit). Tinfoil :
: Tools like NSZ or specialized builders can compress standard NSPs into smaller NSZ files to save storage space on SD cards. How it Typically Works
Homebrew apps such as Tinfoil , Goldleaf , or Awoo Installer are used to browse the SD card and install the update to the console or SD memory. Troubleshooting Common Issues