Pioneer S-IC851-LR CST Series 8-Inch Circular In-Ceiling Speaker (Pair) (Discontinued by Manufacturer) 8-Inch In-Ceiling CST Speaker Coherent Source Transducer (CST) Technology and 1.5-Inch-Inch Aluminum Tweeter Mica-Filled IMPP Woofer Treble and Bass Contour Controls, Phase Control Design and Thermal Resetting Protection Circuit