Silicone tubing, I managed to get a large amount in olive green and clear from Mo's co before he disappeared, and as of yet, don't need to get anymore.
As for shrink tubing, I don't get that from a tackle shop, I go to Maplins and look carefully at the sizes before I purchase what I want. I say that, cos I can't remember what sizes they do, but know it is usually the smallest available that I want.
I don't care that along its length it does have some white writing or printing, cos while the carp are busy trying to squint and read what it says, they are also sucking my bait into their mouth