When these first came onto the market they were extremely expensive and to be honest we all felt that a loop in the end of a stiff rig (which is what they were introduced for) created a more flexible pivot point anyway.
However, the angler, demanded a Size 8 so Korda sourced one and at a far better price than the competition. More recently they have managed to persuade their Japanese supplier of standard swivels to supply the same swivel with a ring on the end at a very competitive price. They now come in the dull grey finish as well, another little edge bearing in mind we have seen from the underwater filming that carp are frightened by the 'glint' of a swivel or hook in clear shallow water when the sun is out.
Besides creating a pivot point for stiff rigs, the ring swivel serves as a massive advantage to most rigs - it allows the hook link to lay flat against the rig tube or leadcore during the cast. This dramatically reduces the risk of a tangle - it sounds far fetched but it's true.
Danny first learned about this in a qualifier for the British Champs. A competitor had a ring swivel on his controller set up which seemed strange, so I asked why to which he replied: "you don't get tangles with a ring swivel on, even with long, light hook links!"
I have used a loop, ring swivel and Kwik link ever since. It's true that you never stop learning. For a time, I started lassoing my hook links on using the ring swivel. Simply tie an overhand loop in the end of the hook link, pass it through the ring of the ring swivel and then pass the end of the hook link through the loop and pull tight. Hey presto the hook link is attached. Simply reverse the procedure then un-attach the hook link - very simple and very fast.