The duo lock slides displayed are what we used trolling for Kings on the Kenai River. Jet divers are used instead of lead sinkers to prevent snagging the bottom. Four persons with lines in the water are in trouble when a snagged line happens with the river current. The jet divers are attached to the sliders as a sixty pound king creates a lot of drag on the jet and the free sliding jet minmizes that drag. With a $13 Kwikfish, jet diver, heavy duty snap awivels on your line, it gets expensive to snag up four lines on a tree stump. jet divers do not sink to the bottom of the river as lead sinkers do.