Dedicated assist hook (with barb) to aim for large migratory fish such as yellowheaded with sinking pencil. 
Single hook: Use the bolt lock "BT - 70", set the size and length of each size, assist line to best condition. 
Adopting thick welding ring to minimize leader's tightening. 
In order to reduce breakage of the assist line by the tooth, it is reinforced with a long shrink tube.