A non-electrical flexible tube inserted through a flexible endoscope, after its placement in the duodenum via the oral cavity, for the endoscopic cannulation of the gastrointestinal ductal system (i.e., the pancreatic, hepatic, and/or common bile ducts) during endoscopic retrograde cholangiopancreatography (ERCP). It is typically a single-lumen device made of radiopaque plastic materials with incremental markings at the distal tip, used to deliver a contrast medium to the ducts for their radiographic visualization; it does not incorporate a balloon. This is a reusable device.