LaCie's 48GB PocketDrive was launched at Macworld Expo.
PocketDrives now have an improved FireWire to IDE bridge, which boosts transfer performance to 35MB per second - twice as fast as most FireWire discs, according to LaCie.
48GB is sufficient for over 20 hours of MPEG-2 video, or over 70 hours of CD-quality audio. PocketDrives all ship with both USB and FireWire connectivity built-in.
Quality loss Guillaume Mazieres, LaCie's vice president of marketing, said: "Our high-capacity PocketDrives are ideal for storing, exchanging and editing large files such as digital video. Our new FireWire-to-IDE bridge eliminates quality and video-frame loss."
The PocketDrives also offer another new feature, called Fluid Dynamic Bearing (FDB) motor technology. This reduces the drives' noise level by 20 per cent, claims LaCie, making them "some of the quietest external drives on the market".
The 48GB PocketDrive costs $849. No UK price or shipping date has been announced for either product.
The company also announced a PocketDVD-ROM drive. This offers speeds up to 8x, so DVD data-transfer rates can reach 10.8MB per second. It reads CDs at 24x and features both USB and FireWire interfaces. The drive costs $299 in the US.