"AQUASONIC 100 ULTRASOUND TRANSMISSION GEL World Standard for Medical Ultrasound Transmission, AQUASONIC 100 is the most widely used gel for diagnostic and therapeutic medical ultrasound. Recommended for all procedures where a viscous gel is required. Features Acoustically correct for the broad range of frequencies used. Completely aqueous, will not stain clothing or damage transducers. Unique ""can't be copied"" formula is hypoallergenic, bacteriostatic, non-sensitizing and non-irritating. No formaldehyde.