The 2006 United States Mint Silver Proof Set includes ten coins in total, five of which are state quarters. The state quarters featured in the set are: Nevada Nebraska Colorado North Dakota South Dakota Each of these quarters features a unique design that represents the history and culture of the state it represents. The coins in this set are struck in 90% silver and have a proof finish, which means they have a polished, mirrored background with frosted raised elements. In addition to the state quarters, the 2006 Silver Proof Set also includes a silver dime, nickel, and half dollar, as well as a silver Kennedy half dollar and a Sacagawea dollar. This set is highly collectible and sought after by coin collectors and enthusiasts.