Attachments for Core Spun Yarn Tailor made attachments for Ring Frames to produce Single Core, Dual Core and Tri Core yarns. CTL – Core Traverse LinkedAttachment for the production of Soft Core yarn. More info Special inner creelsHard core yarn attachment. More info Overhead creelDuo core yarn attachment. More info 3D – Three decksDuo core yarn attachment. More info Hybrid creels and Tri Core yarnUpgradations and Tri Core attachments. More info