DESC: The CRS FOUR features an extremely rigid, but ultra light, hard anodized magnesium alloy woofer cone. This produces bass that is tight, powerful, and beautifully profound.The state-of-the-art woofer also extends mid-range voicing beyond any speaker in its class. It is clear, open and life- like. The tweeter is also made from a hard anodized magnesium alloy; the fastest and most accurate material that can be used. This produces crystal clear highs without sounding harsh or grainy.