I purchased my smok vct a1 at a local vape shop and was told the coils cannot be rebuilt another vape shop had the do it yourself kits for this specific sub ohm tank, the factory coil is a single, but the diy is a dual that tests at .41 my itaste mvp3 loves the diy, the flavor is amazing and so is the cloud, to the smoketek fans out there i highly recomend trying the diy, after watching the build video on youtube