It could be an error. 500 pages or more of website information and mistakes happen. The S indicates Straight. Will take a look at it. CK sells their connectors separately and each connector has 20 configurations it seems. Their excel file looks something like that, but as I said, it extends 5000 items just to get their relatively small line. Don't forget that many companies have 2 or 3 lines, and offer more than TIG products...What you haven't included here is that each torch can be configured with sometimes 5 different gas line configurations, then each one of those can have 10-20 connectors, some gas through dinse 25 some dinse gas through 50, some special fittings like power blocks, some tweco, some dinse 25, some dinse 50, some dinse 90(?), some with quick disconnects and each of those in a fused or unfused configuration. It's not easy and it gets just as confusing looking down a list...that is long.