The Mundorf BS180 coils are high performance coils, ideal for midrange crossovers in subwoofers. The core is made of Feron, which underwent a heat treatment after its production. This treatment gives it an optimal internal structure for good magnetic characteristics offering very low losses and low distortion. Their power handling is also higher than for conventional ferrite core coils. The "Backed Varnish" finish allows to limit vibrations and to use a maximum wire diameter for a reduced electrical resistance.