Vaporesso SKRR Replacement Coils are designed for SKRR Sub Ohm Tank. It has three types optional: QF Strips 0.18ohm coil, QF Meshed 0.18ohm coil, and SK CCELL 0.5ohm coil. QF Meshed coil creates intimate contact with the organic wick for rapid and even heating. QF Strips provides rapid, even heating. QF Strips are the longest-lasting. SK CCELL is including Temperature control through the use of SS316 Coils. All of these will bring you pure flavor and different vaping experience.