At last, a faithful reproduction of the classic "phenolic ring" tweeter developed by CTS and used by Marantz, Altec, and many others! High efficiency and smooth, extended response. Extremely versatile; great for repairing older systems or for new custom projects. Low-mass paper cone and dust cap, 3/4" voice coil, and stamped steel faceplate. 8 ohm nominal impedance. This is a drop in replacement for the Marantz Imperial Series cabinet speakers models Marantz Imperial 4, 5, 6, 6G, 7, 8, and 9 with common part numbers 137-7348N, 137-7350, 137-7816, and 841-1022 and HLM312A. Also used in Radio Shack Nova series cabinets Nova 7b as well as the Altec Lansing Santana 891 speakers, RSL Rogersound Labs, Acoustic Research AR 4x (may require crossover modification for full power handling), Martin Speakers, and Rectilinear XI Cabinets from the 70's.