Aftermarket diaphragm for  dB Technologies Sigma 215, Sigma 115Martin and more 

Voice Coil Diameter  72.2 mm 
Dome  material Titanium (blue)
Impedance 8 Ω
Coil wire ALUMINIUM WIRE
Overall Dimension 106 mm ±1 
Total length   125 mm ±1
The distance of  terminals 39 mm ±1
QTY1pc