The 100-watt C620 gives you the same basic dimensions as the C640, but with the cost advantage of a high-performance polypropylene woofer and silk-dome tweeter. This combination is known for smooth response across its entire spectrum, so you'll get accurate staging and brilliant clarity. You really can have it all.     Design: 2-Way coaxial in-ceiling Tweeter: Pivoting 1” silk dome Woofer: 6.5” Polypropylene cone with rubber surround Sensitivity: 91dB Frequency Response: 36Hz-20kHz Impedance: 8Ω Power Handling: 5-100 Watts Speaker Dimensions: Diameter 9-1/4” X Depth 3-5/8” Cut-Out Diameter: 8-1/4”