Livingstone Conductive Lubricant Clear Gel for Ultrasound and ECG Electrocardiogram, 100% Biodegradable, 250ml in Easy Squeeze Bottle and 4L Specifically made for Ultrasonic, E.C.G., T.E.N.S. And E.M.S. Applications. Use a small amount over skin, rub in with electrode surface and fit firmly. Safe to use on laser treatment machine.