ProTaper – Chains, including the Pro Series Forged 520 racing chain 120L, Pro Series Forged 520 slim O-ring chain 120L, 520XRC 120L, 520MX1 Gold Series chain and 420MX 134L, is the full-length chain selection, cut and packaged in the lengths riders actually order for motocross and off-road machines. Drive chain quality shows up in ways that are easy to feel: consistent tension means the rear wheel drives cleanly out of a rut instead of snatching, and a chain that resists stretch keeps gearing exactly where you set it through a long day of practice. The Pro Series Forged racing chain is aimed at riders who want the strongest plate and pin construction available for hard launches and big-bore power, while the slim O-ring version adds sealed protection against grit and water for trail, enduro and dual purpose use without the bulk of a heavy street chain. The 520XRC and 520MX1 Gold Series remain go-to choices for reliable race weekends, and the 420MX 134L covers smaller displacement bikes. Pair any of them with the correct master link and the driveline stays quiet, smooth and predictable. Confirm sizing against your own sprocket combination before cutting the chain.