Jimmy Fee demonstrates his version of the Uni Knot, which is useful for attaching two different sized fishing lines. Attaching braid to a fluorocarbon leader is the most common Uni-to-Uni Knot method, but it can also be used to tie braid to monofilament. Although the Uni isn’t the strongest in comparison to others like the FG Knot, it’s extremely reliable and one of the easiest in terms of time and difficulty.