Stenner Tubing 1/4" x 20 Feet | AK4002W

Q: Hi, I wanted to ask. In some of the packages, there is a black tubing included. I ordered this tubing some long time before, but would like to know, few things: * what are the main differences between this transparent and the black tubing? Are some of them better for some kind of chemicals, or chemical resistance properties are the same? * is the only difference that the black tubing seems to be more flexible? * is it possible to order just the black tubing? I don't see it available separatelly Best regards, Pavol