These are single voice coil. All JL Audio woofers are single voice coil except W6 and the 13w7.

a voice coil is the electromagnet that causes a speaker horn to move in response to the electrical impulses received from the amplifier.

They will either pull in or push out depending on the polarity of the DC voltage and remain stationary.

This is a bad idea as the DC resistance of the voice coil is much less than the AC impedance of the voice coil and it is possible to overheat and burn out the voice coil due to the much higher current the DC voltage can produce in the voice coil compared to the AC voltage that would drive the voice coil in normal operation.

When connecting a dual voice coil sub in series you should use the powered subs.

The Legacy Car Audio LW1549 comes with a 2.5'' High Temperature Dual Kapton Voice Coil.