Quad Small Form-Factor Pluggable 28, these transceivers are suitable for 100 Gigabit Ethernet , EDR InfiniBand or 32G Fiber Channel Networks. The QSFP28 100Gbps transceiver features four high-speed differential signaling lanes with data rates ranging from 25Gbps (4x25Gbps) to 40Gbps.

The QSFP28 SR4 transceiver requires 8-core fiber, while the QSFP28 LR4 optical module requires a 2-core fiber.

Although both QSFP28-100G-SR4 and QSFP28-100G-LR4 have the QSFP28 form factor and the same speed, they are pretty different. The critical difference is the fiber connector, max distance, wavelength, and supported fiber cable.

The "SR4" designation indicates that it is a 4-fiber connector used for short-range applications, from there “LR4”, means Long Range 4, is a 100G transceiver that employs four separate optical channels to transmit data over a longer distance. It can cover distances of up to 10 kilometers using a single-mode fiber.