Cross compatible with the Smok Baby and Big Baby Beast aside from the NRG tank.The Replacement GT4 Quad Core 0.15 ohm coil head is supporting four individual Kanthal coils that have been wrapped to perfection and wicked with Pure Organic Cotton to bring out even the most subtle undertones in your favorite e-juice flavors. The GT4 Core is constructed out of high grade Stainless Steel and houses four individual wicking ports to ensure that your wicks stay nice and saturated, no matter what. This remarkable replacement coil head is rated for best use between 30-70W and is preferable for anyone that’s looking to extract the most flavor from their e-liquid.