ATOP’s APSP831B53xDL40 single-mode transceiver is SFP28 module for duplex optical data communications support up to 28.05Gb/s. It is with the SFP+ 20-pin connector to allow hot plug capability. Digital diagnostic functions are available via an I2C. It has built-in clock and data recovery (CDR). This module is designed for single-mode fiber.