Yep, the vast, vast, vast, majority of proofs you get are going to be clad proofs. They are cheap, common and coin dealers won't charge you more than a buck or two for the complete set. Silver (1992-present) proof sets are scarcer and rarely find their way into circulation. Silver proofs (1992-present) all have a tell-tale white edge the same as any other 90% silver coin. Like Madwest said, the "S" stands for San Fransisco, not silver.