Check the listing for details. EMB 3-Way Crossover Network w/ Variable Gain Control. Condition: New. Listed at 99.95 USD. EMB 3-Way Crossover Network w/ Variable Gain ControlA Fine Crossover for the Discriminating DIY'er This is a Brand new EMB 3-Way Crossover Network w/ Variable Gain Control. Very large inductor suggests this is for a speaker that has an enormous woofer/subwoofer with a very low crossover frequency. Inductor has diameter of 64mm. Wire coil is 46mm to 64mm in diameter. 24mm thick. Wire appears to be 20Ga. By the dimensions given you should be able to calculate inductance IAW: d²n²L= ------- ×22 In microhenries. n=number of turns, d=diameter of wire (†there are 22 windings from 46mm to 64mm. Set d=57mm (0.057) then square. Then × by 22. Square n, then divide.). 18d+40lThe equation above is ideal, with d=an infinitely-thin, single turn of wire. There are 22 windings from 46mm to 64mm. Set d=57mm (0.057 is the average from 46mm to 64mm) then square. Square n, then multiply the result. Then multiply your result by 22. Divide this number by the numerator in the above equation. The result will give you a very good approximation of this inductor. With capacitor values illustrated in the picture it becomes an easy task, therefore, to calculate octave/dB rolloff. As you can see from the pictures, the manufacturer spares no large expense to use the finest grade capacitors (metallized PETE polymer film at 5% tolerance and a dissipation factor no greater than 1/100 of one percent; i.e., DF