The chain end goes on the ring so you can retrieve the anchor and pull it out of the rocks. The zip keeps the chain lined up towards the end to make it easy to set. Some tie a marker buey or separate retrieval line to the ring and the chain to the end. The end is the best place for the chain so zip it when you throw it out if the thing is not setting. When you pull it up the zip breaks, the chain and ring slide up the anchor for retrieval. In wind and current it can be hard to get the anchor to dig in. The zip just keeps it lined up so it has the best chance to bite. It's not always easy to get an anchor to dig in on the first try. Some even add a 10' line between the ring and the line going to the boat and put a small float on it. This float helps it sink and set in the right orientation. Believe it or not somtimes you have to pull up and throw the anchor out 3 times to get it set in the wind or current. The extra float or zip just help you get it to set on the first try.