The Triton battery has 808/ego threading. The Halo triton tank is really a Kanger T2. The threading is just slightly different and the Triton tank will not work on most 510/ego batteries. However, a Kanger T2 will work on a Triton battery...go figure. The standard T2 leaves a small gap, but nothing very noticeable. Both use the same replacement heads. So, you can buy any standard T2 and any T2 replacement head, and both are much cheaper elsewhere.
I prefer a 1.8 ohm head on the Triton battery.
Smokeless Image products use the same 808/ego threading, and they have a plethora of products that will work on the Halo Triton battery.