The JBX05579 QSFP28 to SFP28 breakout direct attach copper cable represents an essential connectivity solution for modern high-speed datacenter networks. As a direct replacement for Cisco's QSFP-4SFP25G-CU5M, this 5-meter cable delivers enterprise-grade performance at a competitive price point. **Technical Architecture** This passive breakout DAC utilizes premium 26AWG twinax copper construction, specifically engineered to maintain signal integrity across the full 5-meter length. The cable features QSFP28 MSA-compliant connectors on the source side, splitting cleanly into four individual SFP28 connectors, each supporting independent 25Gbps data transmission. This design enables flexible port allocation without requiring active conversion electronics. **Standards Compliance & Certifications** Qualified to IEEE 802.3bj specifications, the JBX05579 meets stringent industry performance benchmarks. Full RoHS and ELV directive compliance (EU 2002/95/EC) ensures environmental responsibility, while TUV and UL certifications validate safety standards. The cable's engineering prioritizes reliability and longevity in demanding network environments. **Performance Characteristics** With a rated data rate of 100GB capacity at QSFP28 input, this breakout cable provides transparent 25GB per-lane performance to each SFP28 output. The passive design eliminates power consumption and latency concerns associated with active conversion modules. Operating temperature range of 0-70°C accommodates both cooled datacenter facilities and edge deployment scenarios. **Deployment Flexibility** Ideal for organizations migrating from 100GB-only infrastructure to mixed-speed networks, this breakout cable maximizes existing switch investments. Common applications include connecting legacy 25GB SFP28-equipped servers to modern 100GB QSFP28 switch ports, enabling gradual network evolution without wholesale equipment replacement. **Quality Assurance** Backed by a 90-day limited warranty, each cable undergoes quality verification. Available with custom brand programming for channel partners and large organizations. Ships from strategically located US warehouses (Danville, CA and Beaufort, SC) with free standard shipping on qualifying orders, ensuring rapid deployment timelines.