FG Knot. Used to join fluorocarbon to braid. Why you need it and how to tie it. The knot comes from Japan. The FG stands for "Fine Grip".
I Found the Ultimate FG Knot Method for Finesse AND Big Game
Uni Knot - One of the best, easily learnt, and strongest fishing knots
Strongest Fishing Knots Connecting Braid to Leader
8 Fishing Knots Every Deckhand Should Know - InTheBite
How to Tie an FG Knot (Sebile Knot)? Steps, Variations & Video
How to Tie the FG Knot (braid to mono): Line-to-Line fishing knot
High Performance Deepwater Groper Rig
How to Tie the FG Knot - USAngler
Wairarapa Trout - Kopouranga, Waipoua and Mangatarere Streams
First FG knot Braid to Braid - Main Forum - SurfTalk