Catheter and a cannula

"The invention provides an assembly of a catheter and a cannula for cooperation therewith, wherein the catheter is provided with visible gradations disposed on the surface of the catheter adjacent it. Catheters are small rubber or plastic tubes that can be inserted through the urethra into the bladder. Catheters are a sure-fire way to empty the bladder. Both men and women can use catheters. Paruretics who use catheters perform what is known as clean-intermittent-catheterization (CIC). That means the catheters are inserted as needed, on an intermittent basis. It also means the catheters don't need to be sterile. They just need to be thoroughly clean. There are also external catheters available that don't need to be inserted into the urethra. They require that you can control the urinary muscles in order to drain your bladder. They have a rubber sleeve that fits over the penis, a collection bag, and a system of valves and drain tubing to connect up to the bag. "