A network interface card for your C64!
The RR-Net MK3 by individual Computers is the third edition of the wellknown network interface and allows the C64 to connect to an intranet.
Response to customer demand, the RR-Net MK3 was so designed that it can be operated without a "carrier-card" directly in the C64. However, it is still compatible with the MMC Replay, MMC64 and Retro Replay where you can connect it into the clockport (for MMC64 use the pass-through of the MMC64).
Using the RR-Net MK3 as a cartridge without carrier card does not work with SX-64 and very old C64 mainboard versions.