Catheter free pH monitoring system is a catheter-free way to measure pH. It is used to measure esophageal pH (acidity) levels in patients who have or are suspected of having gastro esophageal reflux disease. This system involves a pH capsule, about the size of a gel cap that is temporarily attached to the wall of the esophagus. The pH Capsule measures pH levels in the esophagus and transmits readings via radio telemetry to the receiver worn on the patient's belt or waistband.