1mm Tubing: The main use for 1mm silicone is sliding stop knots on a snood line, a moveable bait stop for instance.

1.5mm Tubing: With the increased internal diameter, this is more for use on the rig body, again mainly for sliding stop knots. It can also be used as a stand off on your hook lengths/snoods to help prevent tangles.

2mm: The main application for the 2mm silicone tubing is for stand offs, especially when using Gemini Genie Snood Clips on your hook lengths/snoods.