These plastic clips simply push fit onto your rod blank and povide the perfect tension for clipping your main line, which can be adjsuted slightly depending on how far into the clip you push your line. These clips can be positioned anywhere along the rod blank and the clip arm positioned on top of the blank, on either side, underneath, or anywhere in between. Simple, effective, reliable and hugely popular, there are three diameter clips in the range; these ones are 12mm diameter.