Hi Neil,
They do not look half as good. The stuff I use is really tough and it is already used on your sail at the head and foot. It is not self adhesive - I don't think self adhesive helps. The sail bunches along the bolt rope and this will soon cause the self adhesive stuff to peel off. Also the teflon bit is low friction which is very important when the sail slides up and down the slot.
It has never been on Hydes website. I rang them up and asked for some of it. They charged me about £8 and sent about a metre. They are very helpful. In the past I also scrounged some scraps of the coloured sailcloth for sail repairs.
If you are replacing rivets with screws and nuts make sure that they are short so they do not stick out and damage the sail when you roll it up. Grafham Chandlery had ones which were just the job. If you are calling Hydes you could get a handfull of the rivets when you get the tape
Cheers
Bob
PS If you have trouble with Hydes I have a bit of teflon tape you can have.