These smooth-running powerful performers make trimming easy, no matter how hard the wind blows. Carbo Air blocks are made of tough reinforced composite in a size and style to fit any system: singles, doubles, triples, quads; ratchets and fiddles; soft and hard attach. Perfect for main, jib and spinnaker sheets on dinghies and sportboats; control lines on boats of all sizes. Lightweight, strong and reliable fiber-reinforced composite construction. Ball bearings, sheave, and sideplates are UV-stabilized.