HI there. I recently purchased the Kanger Subtank Mini and the Kanger Subtank Plus. I like both but I'm somewhat new to vaping and I'm trying to figure out which coils are compatible with these 2 units. I see some I buy are vertical and others are horizontal. I've had a lot of out of the box problems with both that I've bought. So much so I'm thinking about buying yet a 4th tank that is not Kanger so I don't have to deal with their crappy coils that are half DOA out of the box. One says 5G and the other says 5D on the side of the 2 I bought. I'm trying to figure out what I'm supposed to be buying for these units. Help appreciated. Thanks.