What is the purpostof the teflon tube that goesover the flex cable ?

[lucozader]

???

[domwilson]

To frustrate you...
It is there to act as a bearing, sleeve, partial lube and seal. Some guys use them, some don't. Some of my boats have them, some don't and some use them only towards the ends of the stuffing tube. Either way, make sure you use a lot of grease on the shaft that runs thru them.