Each sub has 2 coils, they are 4 ohms nominal each.
You wire the two coils together in parallel on each sub (red-red black-black) now you have 1 speaker wire per sub.... the you take the two speaker wires you have left and wire those red-red black-black. Now you have 1 ohm nominal impedance.
Resistance (ohms) will drop in half when you parallel two similar resistances (two 4 ohm coils in parallel = one 2 ohm load) two 2 ohm loads in parallel = one 1 ohm load.
You wire the two coils together in parallel on each sub (red-red black-black) now you have 1 speaker wire per sub.... the you take the two speaker wires you have left and wire those red-red black-black. Now you have 1 ohm nominal impedance.
Resistance (ohms) will drop in half when you parallel two similar resistances (two 4 ohm coils in parallel = one 2 ohm load) two 2 ohm loads in parallel = one 1 ohm load.
