 A 6U board has three such keying blocks, while a 3U board has two.The MultiGig RT2 connector is specifically designed to enable high performance.It accomplishes this through a 7-row 16-wafer (wafers can be power, differential or single-ended) that delivers highly controlled impedance, minimal insertion loss and less than 3% crosstalk at transfer rates up to 6.25 Gbit/s.