The Extreme FireWire (FW) Reader is a high performance reader, which provides you a complete digital system/solution for your photography needs. It offers the highest performance requirement: 40MB/sec (+ or - buffer) sequential read and write. It has one slot for CF (Type I and II). It supports FireWire 800/400 connectivity on both Windows and MAC Operating Systems. It plugs and plays with no external AC power. The Extreme FireWire (FW) Reader supports the Extreme IV CF (Type I and II) cards (all Capacities 2, 4 and 8GB).