This section describes the two receive elastic buffer implementations; one implementation uses the buffer present in the device-specific transceivers, and the other uses a larger buffer, implemented in FPGA logic. If the latter option is selected, the buffer in the device-specific transceiver is bypassed in UltraScale and UltraScale+ families. For 7 series devices the buffer in the device-specific transceiver is not bypassed; however it is read using the recovered clock.