Hydra-Cool Serum may be used with several device modalities. With galvanic iontophoresis and ultrasonic current, anything that contains water and is water soluble may be used. This current needs something water-based in order to effectively conduct. Microcurrent can be used over products that are water or lipid soluble. Having something like Rejuvenating Masque atop the serum will give more slip and glide and enhance current conduction. Check the manufacturer’s instructions and any training materials you may have from the device manufacturer.