Feature●Impedance : 16 Ohm●Voice Coil Diameter : 44.4mm / 1.75" / Outer Ring Diameter : 72mm / 2.8"●The Center Distance Of The Two Post Terminals : ~ 82mm / 3.2"Description This Is A Brand New 18 Sound ORIGINAL FACTORY Replacement Diaphragm,for 18 Sound ND 1070 / ND 1090 / HD 1050