2: The use of a 3ppb OCXO clock running directly at 24MHz and connected via a board track just a couple of inches away from the USB chip. Therefore, no precision is lost within cables and connectors, as is the case when using an external master 10MHz clock with an additional 24MHz clock generator.
3: Two independent Statement-level linear power supplies, one dedicated to the OCXO clock and the other used for powering the USB chip/5V USB line.