The Raven pure ribbon transducers are world-renowned as one of the best high-end loudspeaker drivers available. Raven technology is based upon the use of a pure aluminum ribbon element acting as both the diaphragm and the voice coil. These are 95 dB SPL high sensitivity units at 1w/1m and are using strong neodymium magnets. They were tested, measured and QC passed. Note that the price is for each unit and I have 19 units to sell.