The Murdex RDTA features coil control function that you can set A & B totally 2 sets coils in the atomizer. When start to use Murdex RDTA, you can only use A coil, or only B coil or use A & B coils together. There are Murdex Halo-T RDTA, made from Titanium. And Murdex Halo-S RDTA, made from 316ss. Can you identify from the pics? Which material do you prefer? What are their own advantages? Come on, guys.