Electrodes, TENS, Misc. - Aquasonic 100, Ultrasound Gel, 5 Liter Refillable Dispenser, Case of 4 : Aquasonic 100 ultrasonic gel is a water-based that is non-staining, hypoallergenic, bacteriostatic, non-sensitizing and non-irritating. Recommended for all procedures where a viscous gel is required.