DigiLink cables are designed to connect an HD I/O peripheral (such as 192 I/O or 96 I/O) to an HD PCI card, or an HD I/O to another HD I/O, as two HD I/O's can be chained together (this makes for a single, clean DigiLink connection between multiple I/O's and the CPU). Purchased separately, longer DigiLink cables — 25', 50' and 100'* — are useful for environments in which isolating machine noise-generating CPUs is an issue. *DigiLink 100' does not support sample rates above 96 kHz.