The STLTH LOOP 9K Pods are compatible with both the STLTH LOOP 1 & 2 Devices. However, the e-Liquid indicator will only work while using the 9K Pods with the LOOP 2 device. Using the LOOP 2 Device and the 9K Pods will allow the e-Liquid indicator to function so you will always know how much e-Liquid is left. If you use the LOOP 9K Pods with the LOOP 1 Device you will not be able to see how much e-Liquid was depleted.