For fans of crochet hook this clips will be very useful. I put it in my catalog free pattern. Other clips HOW TO KNIT - MAKING AN I CORD
are located here http://lanahobby.blogspot.com/2009/08/how-to-knit-making-i-cord.html/>
If you are working in sets of 4, you can combine your loops at the single crochet row. There are a few ways that I can think of. The first would be combining 8 loops with 4 single crochet at each end. If you want more of a gradual decrease, you could combine 2 loops with the first set of 4 and two loops with the second set of 4 at both sides. The last way would be to work 2 single crochet on the last two sets of loops on both sides.