CPU multiplier locking is the process of permanently setting a CPU's clock multiplier. AMD CPUs are unlocked in early editions of a model and locked in later editions, but nearly all Intel CPUs are locked and recent models are very resistant to unlocking to prevent overclocking by users. AMD ships unlocked CPUs with their Opteron, FX, Ryzen and Black Series line-up, while Intel uses the monikers of "Extreme Edition" and "K-Series." Intel usually has one or two Extreme Edition CPUs on the market as well as X series and K series CPUs analogous to AMD's Black Edition. AMD has the majority of their desktop range in a Black Edition.