If you want to get a strong bond, place the tippet ring between the leader and tippet to knot. In addition to facilitating tippet replacement, it also has the advantage that the leader side does not shorten for each nodule, reducing leader wear. Furthermore, even when there is a gap in the thread diameter between the leader and tippet (such as when connecting 5X to 3X), the strength of each other can be maximized. It is also very effective when knotting different materials such as tying fluorocarbon to nylon.
It is often used for tight line nymphing and European nymphing styles, but it is also recommended for retrieve fishing using the sinking line. It is suitable for fishing that sinks the fly because the metal part with a little weight is in the middle of the leader tippet, but it will not be a problem in dry fly fishing using thick thread.
Swivels are useful when using swivel flies such as the Woolly bagger with a tightly wrapped hackle. The TMC Tippet Ring Swivel is a tiny swivel that reduces the "twist" of the leader tippet without adversely affecting casting or presentation.
SS: Outer diameter 2.5 mm, strength 21 kg (10 pieces)
S: Outer diameter 3.2 mm, strength 23 kg (10 pieces)
SM: Outer diameter 3.7 mm, strength 21 kg (10 pieces)
Swivel: Strength 7 kg (10 pieces)
Ring 3 size, swivel 1 size.