The Silicone Stoppers from SPRO has been the classic form to attach a stopper to your line for years. The stoppers are made of iron wires with an eye and a silicone stopper on top. You can easily slide that stopper over your line, by putting the line through the eye and folding the line in half, so you pull the stopper over your line. You can obtain them in different sizes. Ideal for various fisheries.