Hooklink material is the line a carp angler uses to tie the rig itself. In this group you will find coated braid, uncoated braid, and fluorocarbon and stiff mono. The stiffness and visibility of the material affect how the rig behaves on the bottom and how the fish meets it.
Coated braid is the most versatile hooklink for carp rigs. The coating makes it stiff and tangle-resistant, but you can strip it back near the hook to create a supple hinge. It works well for bottom bait rigs and many kinds of combi rig, and it gives you control over exactly how the rig lies.
Uncoated braid is soft and supple. It follows the contours of the bottom and lets the hookbait move freely, which helps when the fish are feeding cautiously. It is often fished with a PVA bag or PVA string to stop the rig tangling on the cast.
Fluorocarbon and stiff mono stay straight and are hard to see in the water. They are used to tie chod, stiff hinge and zig rigs as well as ronnie-style rigs, where the stiffness of the hooklink keeps the hook in the right position and helps it turn.
Choose the breaking strain to suit the snags in your swim, and test how the rig behaves in the margin before you cast it out to the spot.