Advantage：

1. Protect the main line: avoid being pulled during the casting process, and avoid damaging the main line and guide ring due to the heat after friction;

2. Wear resistance: When towing the bait, protect the front end of the trunk line and avoid obstacles such as rocks, branches and weeds.

3. Hide the main line: reduce the alertness of the fish after finding the line;

4. Buffering effect: offset the instantaneous tension that may appear, play a buffering effect;

5. Protect the fishing rod: When removing the bait, it can prevent the fishing line from speeding up to avoid hurting people.