The SATA standard defines a data cable with seven conductors (three grounds and four active data lines in two pairs) and 8 mm wide wafer connectors on each end. SATA cables can have lengths up to , and connect one motherboard socket to one hard drive. PATA ribbon cables, in comparison, connect one motherboard socket to one or two hard drives, carry either 40 or 80 wires, and are limited to in length by the PATA specification; however, cables up to are readily available. Thus, SATA connectors and cables are easier to fit in closed spaces and reduce obstructions to air cooling. Although they are more susceptible to accidental unplugging and breakage than PATA, users can purchase cables that have a locking feature, whereby a small (usually metal) spring holds the plug in the socket.