Yarn used in fishing... fishing lines are yarn. The diameters here have to do with millimeters so we have the dimensions 0.16mm 0.18mm 0.21mm 0.23mm 0.24mm 0.25mm 0.28mm 0.30mm 0.35mm 0.40mm 0.45mm 0.50mm 0.200mm 0.245mm 0.275mm 0.300mm… most popular. The diameter has nothing to do with the strength of the thread. Each manufactured yarn come from different weaving materials and have different strengths in the same dimension…. We are simply saying here that a small dimension catches a small fish - a large dimension catches a big fish… in the logic of colloquialism. Are there other larger dimensions? Yes, there are. Are there colored lines? Yes, there are colored but there are also invisible fishing lines / or threads, if you want… Let's see a knot that can join threads of the same and different thickness and is used by fishermen and sailors… A very safe knot!!! crumpled knot…