- Z1 Narrow EPT KMC's latest breakthrough in rust protection. EcoProteQ treatment doubles the rust resistance compared to the RB treatment. Benefits of the smoother coating are less noise, great performance, maximum rust resistance and great look. * 1/2" X 3/32" - 112 Links, pin length 7.3mm * For Internal gear hub / single speed * EcoProTeQ Coating (EPT) Anti-Rust technology * Less maintenance * High reliability * No Drop