This is a Circuit Shop Audio diaphragm made to Electro Voice specs. This diaphragm is a direct replacement for EV part number 81256XX. It fits the EV DH1, DH1A, DH1A-MT, DH1A-WP, DH2012, N/DYM-1 and N/DYM-1-MT drivers. Specs: Overall Diameter - 5.0" * Voice Coil Diameter - 3.0" * DCR - 4.4 ohm * Impedance - 8 ohm. Circuit Shop Audio diaphragms are gaurenteed to fit perfectly and sound just like the original. Dont settle for cheap "aftermarket" diaphragms.