JBJ 28 Gallon Nano Cube Advanced Aquarium with LED Lighting (MT-601) Replacement LED 3 Watt Dawn/Dusk Internal Ballast. Part #15 on the exploded view diagram in the JBJ 28 Gallon Nano Cube Advanced Aquarium Manual (2MB pdf file in new window).
JBJ 28 Gallon Nano Cube Advanced Aquarium with LED Lighting (MT-601) Replacement LED 3 Watt Dawn/Dusk Internal Ballast. Part #15 on the exploded view diagram in the JBJ 28 Gallon Nano Cube Advanced Aquarium Manual (2MB pdf file in new window). This is the new version (and the only one available). It may look different than your current ballast. It's marked as Model: LED-18V700l. As shown in the photo, this Ballast comes without the wires and will need to be wired.