The Seldén eye swivel is designed for control lines close to the deck, as with dinghy jib sheets. The swivel can also be used on bigger boats if the purchase of the tackle is sufficient. One eye swivel on each side is an ideal set up for the vang.
The Seldén mast swivel leads the line with full articulation towards the trimmer. It is mainly used for cunningham, spinnakers etc. The sheave has two optional positions, either for lines coming from above or from below.