Tumbleweed's Secure Transport Server is an appliance for transmitting securely encrypted files via the Web. It thus provides far greater speed and flexibility than physical transport of encrypted disks or other media, while publicly available FTP and instant messaging services lack the degree of security required for most government data files. Combining mobility and security are difficult, but the Secure Transport Server provides a solution with both. In the configuration tested by Government Computer News, the appliance takes up 1U of space. It has an Intel Xeon dual-core processor with 2 gigs of memory, sufficient for typical office file traffic volume, and two 146 gig hard drive, in a mirrored configuration so that there is 100 percent data recovery if one of the drives fails. The tested version of the appliance had a single power supply, but the unit comes with a bay for a second one, allowing power redundancy. Setup is quite simple by the standards of security devices. A limitation of the appliance is that only one file can be sent at a time, but this is unlikely to be a problem in day-to-day use. Tested with a one-gigabyte file, larger than most shared office files, the appliance took about four minutes to upload it and somewhat less to download--it is optimized for downloading, since files are typically uploaded once but multiply downloaded. Somewhat mysteriously, a Windows-based client is priced separately, rather than being sold with the appliance.