The Stonfo Elite Dsic Drag bobbins have a small thumb wheel that has enables the bobbin to have infinite thread adjustment. Simply, spin the wheel to adjust the tension, much like the drag on a reel. The Elite bobbins also have a metal thumb rest with a counter sunk hardened steel tube and a ceramic tip that allows the thread to easily glide through the tube for threading and tying.
The Red #1 is for Freshwater, the Blue #2 is for saltwater, bass bugs or streamers. Made in Italy.