These are a Jig Star innovation. The leader can be safely tied or crimped around the protective grommet without fear of leader knots failing. Usually knots fail because heavy pressure causes leader material to elongate, reducing diameter and strength at the assist hook terminal ring. The grommet protects the leader from hard edged rings and ensures free movement giving more attractive jig action and presentation.
1 - Leader attach to grommet
2 - Jig attach to bigger ring
3 - Assist hook attach to smaller ring