Commodore 64/128 Datel EX64 3 Port Cartridge Port Expander with Reset Button
A reproduction of the Datel EX64 that lets you plug up to three cartridges into you Commodore 64 and switch between them.

The EX64 is fuse protected and features a reset button as well as a LEDs which show the port is on.
 
** This device is not compatible with the Commodore 64 Ultimate or The Ultimate 64