Hi and welcome. The mod you have is not important, the coil must fit the tank itself. If you bought the Cuboid Mini kit, you have a Cubis tank, and any of the coils for it will work in it. If you like to direct lung hit-- as opposed to mouth-to-lung-- then a .5 Stainless coil is an excellent choice, Stainless is very clean-tasting wire, IMHO, and .5Ω is a good place to be for a medium watt vaper. If you are worried about knock-off coils, authentic Joye coils are sold in a box with a scratch-off verification sticker.
You'll know when to change the coil; either the wire will burn out and it won't work at all, or the wick will plug up, get dry, burn, and then taste really foul. Really foul. I promise: you will know. It is likely thicker juice (also sweeter and/or darker colored juice) will plug up coils faster. Once they plug up, burning is not far behind. You can make coils last longer if you build them, especially if you sick rayon. But as has been said, the Cubis is probably not the best tank for that. Another possibility is, you might be able to rebuild your Cubis premade coils. I don't know about that one in particular, but many of them can be. Welcome to the board.
