Recommended for all procedures where a viscous gel is required. Aquasonic 100 Ultrasound Transmission Gel expires 5 years from the date of manufacture, as long as it's stored out of the light and at room temperature. If you use a warmer for the gel, it only lasts for around 3 months. Aquasonic 100 Ultrasound Transmission Gel is the most widely used gel for diagnostic and therapeutic medical ultrasound.