The EasyFlash 3 is a programmable cartridge for a Commodore 64 computer that allows multiple KERNAL ROM images and EasyFlash banks.
It is the big brother to the original EasyFlash cartridge, providing compatible functionality, but now allows up to seven banks instead of just one. Adding a KERNAL ROM (such as JiffyDOS) to your C64 has never been easier!
The cartridge also has a USB port for firmware updates and image flashing.
More information: http://skoe.de/easyflash/