At the heart of the NeuroLog System is the NL905 or NL900D Case and Power Supply Unit. These cases not only house and power the various modules, but they also provide a cable free communication between modules. This not only reduces costs, but also keeps the front panel controls free of tangled wires. The NL905 is a compact bench-top unit that can hold up to 4 modules, while the NL900D is a 19″ rack or bench-mountable alternative that accommodates up to 13 modules. Each can be supplied with blank panels to cover unused slots.