Rectangular transparent tubing formed in a vacuum system has some inherent problems in clarity. For one, the vacuum sizer heads need to be long to combat the vacuum's tendency to round the tube. This tends to introduce drag lines and chatter marks. We have long been known for the clarity of our rectangular tubing, but now new secondary techniques are producing a very clear and attractive rectangular tube. Below is a picture of a 2.5" x 4.875" Inner Dimension CAB (Cellulose Butyrate) Rectangular tube used for a three-tier helix in cup transport.From the picture on the right you can see the clarity of this tube.