331-5308-PCWA is a 100% Dell compatible 1000BASE-SX 550m MMF 850nm SFP transceiver module, equivalent to 331-5308. This transceiver can be mixed and deployed with Dell OEM transceivers for seamless network performance and interoperability. PC Wholesale contracts with similar (and sometimes the same) manufacturers as the OEM to build our transceivers. We purchase the same MSA spec, OEM quality optical transceivers as any router, switch, or server manufacturer. Optical transceivers from PC Wholesale carry the same high level of quality in discrete hardware, firmware, packet integrity, and laser strength as the manufacturer's 'approved' OEM. All transceivers are guaranteed for life and returns within 30 days are granted automatically.