Seldén Sail Entry Tongue is a mast or boom service fitting for compatible Seldén spar systems. Selden tongue for sail entry gate. Sail slides are fed in to this spring-loaded gate. When reefing, the sail slides pass through the closed gate down to the boom, holding the sail in place and facilitating fast and safe reefing. Large size for: E138. It is intended for replacement, maintenance or completion of the corresponding original spar assembly. Because Seldén has used several mast and boom sections over many years, check the existing component, section profile and fixing dimensions before ordering. Where an article number is shown, use it as the primary identifier and do not assume that a visually similar fitting from another spar section will be interchangeable.