Tracewell S27 provides space for up to 12 front loading VME boards and 12 rear loading transition cards. The unit has flush front and rear cardcages for unrestricted external cable access, with plenty of space for internal cabling as well. Occupying only 8U of total rack space, multiple systems can be stacked for 19" rack or bench-top operation without effecting cooling performance. Durable construction includes a formed steel cardcage and .125" thick aluminum sides to add strength without excessive weight. Cooling is provided by two 130cfm high-pressure fans drawing filtered air through the chassis and exhausting through the rear panel. A removable rear fan assembly allows access to the power supply and internal wiring, and reduces service time. The power supply includes a 250 or 500 watt option, which provides up to 80 amps on +5V. Both power options have power factor correction and universal AC input. The 12-slot backplane supports both 32 and 64 bit protocol, and features auto-configuration and SMD/ press-fit assembly for speed and reliability. Other options include a front storage bay housing up to four 5.25" half-height devices and rack slides.