This is a Circuit Shop Audio diaphragm made to Mackie specs. This diaphragm fits Mackie C300Z, SRM450, S215, S225, SA1521, SR1522Z and other speakers. It fits the Mackie 0008093, 77005-014 and DC10/1710-8 Drivers. The Mackie part number is 0025666. Specs: Overall Diameter - 2.78" * Length - 4.18" * Voice Coil Diameter - 1.75" * DCR - 6.7 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.