As mentioned, the line (or drop) attaches to the decoy and to the weight. In decades past, these were nearly always pieces of nylon line cut off a spool to the correct size. Stronger, more rigid kinds of line are the norm nowadays, and they have several advantages, including not fraying, being more waterproof and being much more tangle-free. Many are even rigged with swivels at one or both ends for attaching to the decoy and anchor, and some come pre-rigged with an anchor attached. One important thing to consider is depth. Most dabbling ducks are hunted with decoys set in just a couple of feet of water or less, so 3-foot lines work fine. If you'll be hunting deeper water than that, use lines that are long enough to still allow your decoy good movement.