I have an Aspire Pegasus (with a IMR 18650 battery) of which putting a new atomiser on it it asks which type of metal including Kanthal, Nickel (I think), and Titanium. Do I need to have those specific coil types within the RDA to be safe or make it work? I also have an iStick power mod which just allows you to set the wattage and that's really it. Would it be wise to use this mod? I'm also wondering which type of metal/coil to get which suits the RDA best of which is a Wolfteeth RDA clone. I also see that prebuilt coils have a size of sorts? for example 24 AWG or 22 AWG. Not sure what that means. Thanks for any help that's provided and any information on RDA's is very helpful.