If you need to use monofilament or fluorocarbon that tests heavier than approximately 60 pounds, you need to buy a crimp kit and forget about knots. Lines this heavy are very stiff. They don’t like to bend, conform, or compress tightly enough to properly tie any of the knots outlined here. Heavy lines are usually fitted with a metal sleeve that gets squeezed tight with a set of crimping pliers after the line is passed through the sleeve, through the eye, then back through the sleeve in a U shape.