Brand: Sure Guard Size: 250mL Ultrasound imaging is a widely used technique in every health care center and hospital. Ultrasound gel is used as a coupling medium in all ultrasound procedures to replace air between the transducer and the patient’s skin, as ultrasound waves have trouble in traveling through air. Ultrasound gel is composed of a mix of propylene glycol and water. Propylene glycol is a synthetic product that is commonly found in hygiene, cosmetic and food products. It is quite sticky and thick. It’s important for it to have a sticky texture so that it stays on your skin and doesn’t drip off when the ultrasound is being performed.