A standard TT is marked with the following:

• Size: Internal diameter (ID) in mm. Sizes 2-9 (Fig 1)
• Length: The distance from the tip of the tube is marked along the tube’s length. Tubes are produced longer than required, and can be cut to the appropriate length (Fig 2)
• Implantation testing: The letters IT or Z79-IT denote that the device material has been tested in rabbit muscle, to ensure tissue compatibility (Fig 3)
• Radio-opaque line: To aid detection on x-rays