Infinity 329CF 105W Peak 3-1/2 Inch Custom Fit Two-Way Speakers (Pair) The Kappa 32.9cf 3-1/2-Inch speakers feature light, but stiff woven glass-fiber woofer cones that won't flex or distort. Plus One woofer cones This patent pending technology deliver a cone with more surface area than competing models of the same size.