Owner C'ultiva Solid Ring P-14 Inner diameter 4mm (80lb)

Size: #4 / Strength: 80lb / Inner diameter: 4mm / Outer diameter: 6.4mm / Wire diameter: 1.2mm

This ring has no seams or contact points. It's made by punching out stainless steel plate into a ring, which is then polished. So naturally, it boasts incredible strength both structurally and in terms of the material.
What's more, the polishing process makes the surface smooth, so there's almost no friction, deterioration, or damage when tying it to a braided line or leader.