This five pack of replacement coils is manufactured by SMOK, a trusted leader in the vaping industry, and is compatible with the SMOK Micro TFV4 Tank. The coils are 0.25ohm and they are constructed from stainless steel. Its dual core give them an ability to sense temperate, meaning that you will not have any burnt flavor invading your vaping experience. There are particularly well suited for 30W to 60W. Flavor is enhanced with these coils.